Extended wear ophthalmic lens

ABSTRACT

An ophthalmic lens suited for extended-wear for periods of at least one day on the eye without a clinically significant amount of corneal swelling and without substantial wearer discomfort. The lens has a balance of oxygen permeability and ion or water permeability, with the ion or water permeability being sufficient to provide good on-eye movement, such that a good tear exchange occurs between the lens and the eye. A preferred lens is a copolymerization product of a oxyperm macromer and an ionoperm monomer. The invention encompasses extended wear contact lenses, which include a core having oxygen transmission and ion transmission pathways extending from the inner surface to the outer surface.

This application is a divisional of application Ser. No. 08/569,816,filed Dec. 8, 1995, which is a continuation-in-part of U.S. applicationSer. No. 08/301,166, filed on Sep. 6, 1994, now abandoned. Priority isalso claimed under 35 U.S.C. 119 for German Application No. 95810221.2filed on Apr. 4, 1995 and Swiss Application No. 1496/95 filed on May 19,1995.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates broadly to lenses and polymeric materials usefulin optic and ophthalmic arts. More specifically, this invention relatesto polymeric materials and treatment processes useful in the manufactureof contact lenses. Still more specifically, this invention relates tocontact lenses useful as extended-wear contact lenses.

2. Description of the Related Art

A wide variety of research has been conducted in the field ofbiocompatible polymers. The definition of the term "biocompatible"depends on the particular application for which the polymer is designed.In the field of ophthalmic lenses, and in particular in the field ofcontact lenses, a biocompatible lens may be generally defined as onewhich will not substantially damage the surrounding ocular tissue andocular fluid during the time period of contact. The phrase"ophthalmically compatible" more appropriately describes thebiocompatibility requirements of ophthalmic lenses.

One ophthalmic compatibility requirement for contact lenses is that thelens must allow oxygen to reach the cornea in an amount which issufficient for long-term corneal health. The contact lens must allowoxygen from the surrounding air to reach the cornea because the corneadoes not receive oxygen from the blood supply like other tissue. Ifsufficient oxygen does not reach the cornea, corneal swelling occurs.Extended periods of oxygen deprivation causes the undesirable growth ofblood vessels in the cornea. "Soft" contact lenses conform closely tothe shape of the eye, so oxygen cannot easily circumvent the lens. Thus,soft contact lenses must allow oxygen to diffuse through the lens toreach the cornea.

Another ophthalmic compatibility requirement for soft contact lenses isthat the lens must not strongly adhere to the eye. Clearly, the consumermust be able to easily remove the lens from the eye for disinfecting,cleaning, or disposal. However, the lens must also be able to move onthe eye in order to encourage tear flow between the lens and the eye.Tear flow between the lens and eye allows for debris, such as foreignparticulates or dead epithelial cells, to be swept from beneath the lensand, ultimately, out of the tear fluid Thus, a contact lens must notadhere to the eye so strongly that adequate movement of the lens on theeye is inhibited.

While there exist rigid gas permeable ("RGP") contact lenses which havehigh oxygen permeability and which move on the eye, RGP lenses aretypically quite uncomfortable for the consumer. Thus, soft contactlenses are preferred by many consumers because of comfort. Moreover, acontact lens which may be continuously worn for a period of a day ormore (including wear during periods of sleeping) requires comfort levelswhich exclude RGP lenses as popular extended-wear candidates.

In order to balance the ophthalmic compatibility and consumer comfortrequirements in designing a daily wear soft contact lens, polymers andcopolymers of 2-hydroxyethyl methacrylate (HEMA) were developed. Thesehydrophilic polymers move well on the eye and provide sufficient oxygenpermeability for daily wear. Certain soft contact lenses have beenapproved by the FDA for extended wear periods of up to about 6 nights ofovernight wear and seven days of daily wear. However, the consumercannot safely and comfortably wear these poly(HEMA) lenses for extendedperiods of seven days or more, because the oxygen permeability isinsufficient. True extended wear (i.e., seven days or more) of theselenses may result, at a minimum, in corneal swelling and development ofsurface blood vessels in the cornea.

In order to improve oxygen permeability, polymers containing siliconegroups were developed. A variety of siloxane-containing polymers havebeen disclosed as having high oxygen permeability. For example, see U.S.Pat. Nos. 3,228,741; 3,341,490; 3,996,187; and 3,996,189. However,polysiloxanes are typically highly lipophilic. The properties (e.g.,lipophilicity, glass transition temperature, mechanical properties) ofknown polysiloxanes has resulted in contact lenses which adhere to theeye, inhibiting the necessary lens movement. In addition, polysiloxanelipophilicity promotes adhesion to the lens of lipids and proteins inthe tear fluid, causing a haze which interferes with vision through thelens.

There have been attempts to blend the desirable hydrophilic propertiesof hydrophilic polymers, formed from monomers such as HEMA, with thedesirable oxygen permeability of polymers formed fromsiloxane-containing monomers. For example, see U.S. Pat. Nos. 3,808,178;4,136,250; and 5,070,169. However, prior attempts at producing a trueextended wear contact lens have been unsuccessful, either because of theeffect of the extended-wear lens on corneal health or because the lenswould not move on the eye. Thus, there remains a need for anophthalmically compatible, transparent polymeric material which issuited to extended periods of continuous contact with ocular tissue andtear fluid.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the invention is to provide a material having a balance ofoxygen permeability, ion permeability, on-eye movement and tearexchange, all of which are sufficient for corneal health and wearercomfort during extended periods of continuous wear.

Another object of the invention is to provide an ophthalmic lens capableof extended continuous wear periods of at least 24 hours withoutsubstantial adverse impact on ocular health or consumer comfort, andmore preferably, to provide a lens capable of continuous wear of 4 to 30days or more without substantial adverse impact on ocular health orconsumer comfort.

A further object of the invention is to provide an ophthalmic lenscapable of extended continuous wear periods of at least 24 hours withoutsubstantial corneal swelling or consumer discomfort, and morepreferably, to provide a lens capable of continuous wear of 4, 7, 14 or30 days or more without substantial corneal swelling or consumerdiscomfort

Yet another object of the invention is to provide methods of forming anextended-wear ophthalmic lens.

Still a further object of the invention is to provide methods of testingand classifying ophthalmic lenses as candidates for true extended-wear.

These and other objects of the invention are met by the variousembodiments described herein.

One embodiment of the invention is an ophthalmic lens, suited toextended periods of wear in continuous, intimate contact with oculartissue and tear fluid. The lens displays a balance of oxygenpermeability and ion permeability sufficient to maintain good cornealhealth, adequate movement of the lens on the eye and wearer comfortduring extended wear periods. The lens is formed by polymerization,preferably copolymerization, of (a) at least one oxyperm polymerizablematerial which is capable of polymerizing to form a polymer having ahigh oxygen permeability; and (b) at least one ionoperm polymerizablematerial which is capable of polymerizing to form a polymer having ahigh ion permeability. Preferably, the lens includes a core polymericmaterial and ophthalmically compatible surfaces. In a preferredembodiment, the surface is more hydrophilic and lipophobic than the corepolymeric material.

Another embodiment of the invention is a method of forming an ophthalmiclens having high oxygen permeability and high ion permeability. Themethod includes the step of forming a core material, having an innersurface and an outer surface, such that at least one pathway for iontransport and at least one pathway for oxygen transport are present fromthe inner to the outer surface. In a preferred embodiment, the methodincludes treating the surface of the lens to render the surface morehydrophilic than the core.

A further embodiment of the invention is an ophthalmic lens comprising apolymeric material which has a high oxygen permeability and a high ionor water permeability, the polymeric material being formed from at leastone polymerizable material including (a) at least one oxyperm segmentand (b) at least one ionoperm segment. The lens displays a balance ofoxygen permeability and ion permeability sufficient to maintain goodcorneal health, adequate movement of the lens on the eye and wearercomfort during extended wear periods.

Yet another embodiment of the invention is a method of using a contactlens having both an oxygen transmission pathway and an ion transmissionpathway from inner to outer surface as an extended wear lens. The methodincludes (a) applying the lens to the ocular environment and (b)allowing the lens to remain in intimate contact with the ocularenvironment for a period of at least 24 hours without substantialadverse impact on corneal health or wearer comfort. A preferred methodincludes additional steps of(c) removing the lens from the ocularenvironment; (d) disinfecting the lens; (e) applying the lens to theocular environment; and (f) allowing the lens to remain in intimatecontact with the ocular environment for a period of at least anadditional 24 hours. In a preferred embodiment, the lens is worn for acontinous period of at least seven days without substantial adverseimpact on corneal health or wearer comfort.

OUTLINE OF DESCRIPTION OF THE PREFERRED EMBODIMENTS

I. DEFINITION OF TERMS

II. CORE POLYMER AND LENS

A. Oxyperm polymerizable materials

B. Ionoperm polymerizable materials

C. Weight ratio of oxyperm to ionoperm polymerizable materials

D. Morphology

E. Bulk Water Content

F. Ion and Water Permeability

1. Ionoflux Ion Permeability Measurements

2. Ionoton Ion Permeability Measurements

3. Hydrodell Water Permeability Measurements

G. Oxygen Permeability and Transmissibility

H. Mechanical On-eye Movement Parameters

1. Tensile Modulus and Short Relaxation Time

2. Tangent Delta

3. Parameter Combinations

I. Examples of suitable materials

1. Material "A"

2. Material "B"

3. Material "C"

4. Material "D"

III. OPHTHALMICALLY COMPATIBLE SURFACES

IV. UTILITY

A. Ophthalmic lenses

B. Contact lenses

V. METHODS OF USE AS EXTENDED-WEAR LENSES

VI. METHODS OF MANUFACTURE OF LENSES

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of the present invention is an ophthalmically compatible,transparent lens suited to extended periods of continuous contact withocular tissue and tear fluids. A particularly preferred embodiment ofthe invention is an extended-wear vision correction lens suited for safeand comfortable long term wear without removal. In order to properlydescribe the invention and to delineate the metes and bounds of theclaims, a set of basic terms will be defined at the outset.

I. DEFINITION OF TERMS

An "ophthalmic lens", as used herein, refers to lenses which are placedin intimate contact with the eye or tear fluid, such as contact lensesfor vision correction (e.g., spherical, toric, bifocal), contact lensesfor modification of eye color, ophthalmic drug delivery devices, oculartissue protective devices (e.g., ophthalmic healing promoting lenses),and the like. A particularly preferred ophthalmic lens is anextended-wear contact lens, especially extended-wear contact lenses forvision correction.

A "polymerizable material which is capable of polymerizing to form apolymer having a high oxygen permeability", as used herein, refers tomonomers, oligomers, macromers, and the like, and mixtures thereof,which are capable of polymerizing with like or unlike polymerizablematerials to form a polymer which displays a relatively high rate ofoxygen diffusion therethrough. For convenience of reference, thesematerials will be referred to herein as "oxyperm polymerizablematerials" and the resultant polymers will be referred to herein as"oxyperm polymers".

The "oxygen transmissibility"of a lens, as used herein, is the rate atwhich oxygen will pass through a specific ophthalmic lens. Oxygentransmissibility, Dk/t, is conventionally expressed in units ofbarrers/mm, where t is the average thickness of the material in units ofmm! over the area being measured and "barrer" is defined as:

     (cm.sup.3 oxygen)(mm)/(cm.sup.2)(sec)(mm Hg)!×10.sup.-9

The "oxygen permeability", Dk, of a lens material does not depend onlens thickness. Oxygen permeability is the rate at which oxygen willpass through a material. Oxygen permeability is conventionally expressedin units of barrers, where "barrer" is defined as:

     (cm.sup.3 oxygen)(mm)/(cm.sup.2)(sec)(mm Hg)!×10.sup.-10

These are the units commonly used in the art. Thus, in order to beconsistent with the use in the art, the unit "barrer" will have themeanings as defined above. For example, a lens having a Dk of 90 barrers("oxygen permeability barrers") and a thickness of 90 microns (0.090 mm)would have a Dk/t of 100 barrers/mm ("oxygen transmissibilitybarrers"/mm).

A "polymerizable material which is capable of polymerizing to form apolymer having a high ion permeability", as used herein, refers tomonomers, oligomers, macromers, and the like, and mixtures thereof,which are capable of polymerizing with like or unlike polymerizablematerials to form a polymer which displays a relatively high rate of ionor water permeation therethrough. For convenience of reference, thesematerials will be referred to herein as "ionoperm polymerizablematerials" and the resultant polymers will be referred to herein as"ionoperm polymers".

A "macromer", as used herein, refers to a polymerizable material whichhas a molecular weight of at least about 800 grams/mol. The term"macromer", as used herein, also encompasses oligomers.

A "monomer", as used herein refers to a polymerizable material which hasa molecular weight of less than about 800 grams/mol.

A "phase", as used herein, refers to a region of substantially uniformcomposition which is a distinct and physically separate portion of aheterogeneous polymeric material. However, the term "phase"does notimply that the material described is a chemically pure substance, butmerely that certain bulk properties differ significantly from theproperties of another phase within the material. Thus, with respect tothe polymeric components of a lens, an ionoperm phase refers to a regioncomposed of essentially only ionoperm polymer (and water, whenhydrated), while an oxyperm phase refers to a region composed ofessentially only oxyperm polymer.

A "continuous phase", as used herein, refers to a region ofsubstantially uniform composition which forms a continuous pathway fromone surface of an article to another surface of an article.

"Co-continuous phases", as used herein, refers to at least two regions,each of substantially uniform composition which differs from the other,and each of which forms a continuous pathway from one surface of anarticle to another surface of an article. Thus, an ophthalmic lenshaving co-continuous phases of oxyperm polymer and ionoperm polymer willhave two continuous pathways or sets of continuous pathways extendingfrom the inner surface of the lens to the outer surface of the lens.

"Morphology", as used herein, refers to the structure and relationshipof the phases of a material.

"Ophthalmically compatible", as used herein, refers to a material orsurface of a material which may be in intimate contact with the ocularenvironment for an extended period of time without significantlydamaging the ocular environment and without significant user discomfort.Thus, an ophthalmically compatible contact lens will not producesignificant corneal swelling, will adequately move on the eye withblinking to promote adequate tear exchange, will not have substantialamounts of lipid adsorption, and will not cause substantial wearerdiscomfort during the prescribed period of wear.

"Ocular environment", as used herein, refers to ocular fluids (e.g.,tear fluid) and ocular tissue (e.g., the cornea) which may come intointimate contact with a contact lens used for vision correction, drugdelivery, wound healing, eye color modification, or other ophthalmicapplications.

"Hydrophilic", as used herein, describes a material or portion thereofwhich will more readily associate with water than with lipids.

A "hydrophilic surface ", as used herein, refers to a surface which ismore hydrophilic and lipophobic than the bulk or core material of anarticle. Thus, an ophthalmic lens having a hydrophilic surface describesa lens having a core material having a certain hydrophilicitysurrounded, at least in part, by a surface which is more hydrophilicthan the core.

The "outer surface"of a lens, as used herein, refers to the surface ofthe lens which faces away from the eye during wear. The outer surface,which is typically substantially convex, may also be referred to as thefront curve of the lens. The "inner sure" of a lens, as used herein,refers to the surface of the lens which faces towards the eye duringwear. The inner surface, which is typically substantially concave, mayalso be referred to as the base curve of the lens.

"TRIS", as used herein, refers to3-methacryloxypropyltris(trimethylsiloxy)silane, which is represented byCAS No. 17096-07-0. The term "TRIS"also includes dimers of3-methacryloxypropyltris(trimethylsiloxy)silane.

"Molecular weight" of a polymeric material (including monomeric ormacromeric materials), as used herein, refers to the number-averagemolecular weight unless otherwise specifically noted or unless testingconditions indicate otherwise.

A. Oxyperm Polymerizable Materials

Oxyperm polymerizable materials include a wide range of materials whichmay be polymerized to form a polymer displaying a relatively high oxygendiffusion rate therethrough. In addition, these materials must berelatively ophthalmically compatible. These oxyperm polymerizablematerials include, without limitation thereto, siloxane-containingmacromers and monomers, fluorine-containing macromers and monomers, andcarbon-carbon triple bond-containing macromers and monomers. The oxypermmacromer or monomer may also contain hydrophilic groups.

Preferred oxyperm polymers are those formed from a siloxane-containingmacromer. Macromers having dialkyl siloxane groups, especially dimethylsiloxanes, are particularly preferred. These macromers are broadlyreferred to as poly(dimethyl siloxanes) (also, PDMS). Thesiloxane-containing macromer may also include hydrophilic groups.Examples of suitable siloxane-containing macromers include, withoutlimitation thereto, the Materials A, B, C, and D as described herein.

The oxygen transmissibility (Dk/t) of the lens is preferably at least 70barrers/mm, more preferably at least 75 barrers/mm, and most preferablyat least 87 barrers/mm. The lens center thickness is typically more thanabout 30 microns, preferably about 30 to about 200 microns, morepreferably about 40 to about 150 microns, even more preferably about 50to about 120 microns, and most preferably about 60 to about 100 microns.

The oxygen transmissibility of the extended-wear lens from the outersurface to the inner surface must be sufficient to prevent anysubstantial corneal swelling during the period of extended wear. It isknown that the cornea swells approximately 3% to 4% during overnightperiods of sleep when the eyelids are closed, as a result of oxygendeprivation. It is also known that wearing a typical contact lens, suchas ACUVUE (Johnson & Johnson), for a period of about 8 hours (overnightwear) causes corneal swelling of about 11%. However, a preferredextended-wear contact lens will produce, after wear of about 24 hours,including normal sleep periods, corneal swelling of less than about 8%,more preferably less than about 6%, and most preferably less than about4%. A preferred extended-wear contact lens will produce, after wear ofabout 7 days, including normal sleep periods, corneal swelling of lessthan about 10%, more preferably less than about 7%, and most preferablyless than about 5%. Thus, the extended-wear lens must have oxypermpolymer in an amount sufficient to produce oxygen diffusion pathwaysfrom the outer surface to the inner surface of the lens which aresufficient to yield the above properties relating to corneal swelling.Preferably, the extended-wear lens has a continuous phase of oxypermpolymer extending from the outer surface to the inner surface of thelens.

B. Ionoperm Polymerizable Materials

Ionoperm polymerizable materials include a wide range of materials whichmay be polymerized to form a polymer displaying a relatively high iondiffusion rate therethrough. In addition, these materials must berelatively ophthalmically compatible. These ionoperm polymerizablematerials include, without limitation thereto, acrylates andmethacrylates, such as 2-hydroxyethyl methacrylate, acrylamide,methacrylamide, and dimethylacrylamide; poly(alkylene glycols), such aspoly(ethylene glycol); N-vinyl pyrrolidones such asN-vinyl-2pyrrolidone; and the like and mixtures thereof. Other ionopermmaterials are disclosed in the specific embodiments of Materials A-D,described below.

C. Weight Ratios

The ratios of oxyperm to ionoperm polymerizable materials may varysubstantially, depending on the selected balance of oxygen permeabilityand ion permeability for the chosen end-use of the molded polymericarticle. Preferably, the volumetric ratio of oxyperm to ionopermmaterial (including water) in the fully hydrated lens is about 40 toabout 60 to about 60 to about 40. However, weight percentages, based onthe total weight of the lens, will be defined because weight percentagesare more conveniently utilized in lens fabrication. Preferably, theextended-wear contact lenses having substantially only ionoperm andoxyperm materials will have about 60 to about 85 weight percent oxypermpolymerizable material and about 15 to about 40 weight percent ionopermpolymerizable material in the prepolymerization mixture, based on totalpolymerizable material weight. More preferably, the prepolymerizationmixture will contain about 70 to about 82 weight percent oxypermpolymerizable material and about 18 to about 30 weight percent ionopermpolymerizable material, based on total polymerizable material weight.

A wide variety of additional polymerizable materials may be included inthe mixture prior to polymerization. Cross-linking agents, such asethylene glycol dimethacrylate (EGDMA), may be added to improvestructural integrity and mechanical strength. Antimicrobialpolymerizable materials such as poly(quaternary ammonium) salts may beadded to inhibit microbial growth on the lens material. Also, additionalionoperm monomers or macromers and oxyperm polymerizable materials maybe added to adjust the oxygen permeability and ion permeability of thefinal molded article. An especially advantageous polymerizable materialis TRIS, which may act both to increase oxygen permeability and toimprove the modulus of elasticity.

A preferred prepolymerization mixture will include (a) about 30 to 60weight percent oxyperm macromer, (b) about 20 to 40 weight percentionoperm polymerizable material, and (c) about 1 to 35 weight percentTRIS, based on the total lens weight. More preferably, the amount ofTRIS is about 10 to 33 weight percent, based on the totalprepolymerization mixture weight.

In a preferred embodiment, the prepolymerization mixture includes lessthan about 5 weight percent cross-linking agent based on the totalprepolymerization mixture weight. More preferably, the prepolymerizationmixture includes less than about 2 weight percent cross-linking agent,based on the total prepolymerization mixture weight. Even morepreferably, the prepolymerization mixture includes substantially nocross-linking agent. In a particularly preferred embodiment, theprepolymerization mixture includes no added cross-linking agent.

The previously described ranges for oxyperm polymerizable materials,ionoperm polymerizable materials, and TRIS are offered to enable thereader to better comprehend the invention. However, it should be notedthat the specific weight or volume percentages of oxyperm and ionopermpolymerizable materials are not the most critical factors to consider inpreparing a good extended-wear ophthalmic lens. More importantly, thelens must have sufficient ion permeability for good on-eye movement andsufficient oxygen permeability for good corneal health during theextended wear period.

D. Morphology

One requirement of the lens material is that the lens allow a highvisible light transmission from the outer to inner surface of the lens.A lens morphology which includes large phase separated regions willreduce visible light transmission and cause substantial undesirableimage distortion, thereby destroying the value of the lens as a visioncorrection device. Thus, the lens must have a morphology which allows atleast about 80%, more preferably about 90%, visible light transmissionand does not produce any significant undesirable image distortion.

In one preferred embodiment, the lens material has at least two phases:the phases including at least one oxyperm phase and at least oneionoperm phase. While there may be two distinct phases, it is believedthat there may be a transition phase, or interphase, in which thematerial composition and the material properties are a blend of those ofthe oxyperm and ionoperm materials. Thus, there may exist a distinctoxyperm phase or plurality of distinct oxyperm phases, a distinctionoperm phase or a plurality of distinct ionoperm phases, and anamphipathic phase mixture or blend of oxyperm and ionoperm phases. Inone preferred embodiment, the glass transition temperature (Tg) of theoxyperm phase is less than about -115° Celsius.

The existence of separate oxyperm and ionoperm phases, rather than acomplete blend of oxyperm and ionoperm phases, is believed to beadvantageous in promoting the diffusion of oxygen and ions. Oxygen willdiffuse predominantly through the oxyperm polymer, while the ionopermpolymer provides a higher barrier to oxygen diffusion. Similarly, ionswill diffuse well through the ionoperm polymer, but the oxyperm polymerprovides a higher resistance to ion diffusion. Thus, one homogeneousoxyperm/ionoperm phase will provide undesirable resistance to bothoxygen and ion diffusion, while two separate oxyperm and ionoperm phaseswill provide low resistance pathways for transmission of both oxygen andions or water. Thus, the ideal extended-wear lens has a pathway orseries of pathways from the outer surface to the inner surface fortransmission of oxygen therethrough, and an analogous continuous pathwayor series of pathways for transmission of water or ions therethrough. Ina particularly preferred embodiment, the lens has two co-continuousphases, one an oxyperm phase and the other an ionoperm phase, allowingfor permeation of water or ions and oxygen between the front and basecurves of the lens.

E. Bulk Water Content

The measurement of water content is difficult because the removal ofadhered surface droplets, without affecting the bulk lens water content,is difficult. In addition, water may evaporate from the lens surfacequickly, thereby lowering the water content from the equilibrium level.Accordingly, a discussion of the bulk water content of a lens warrants adiscussion of the measurement technique used to determine the watercontent.

The preferred bulk water content of the hydrated lens will be a functionof the lens material properties. The material properties are dependenton the prepolymerization macromers and monomers and polymerizationconditions. Thus, the preferred water content for a lens including afluorine-containing oxyperm material may be different from that of alens including a siloxane-containing oxyperm material. Accordingly,while general ranges for bulk water content are offered for a betterunderstanding of the invention, the invention is not generally limitedto specific bulk water contents.

One method of measuring the water content of a lens formed in accordancewith the present invention, referred to herein as the "Bulk Technique",is as follows. First the lens is thoroughly hydrated in a physiologicalsaline solution, such that the water in the lens is in equilibrium withthe surrounding water. Next the lens is gently blotted between twolint-free blotting cloths to remove surface moisture. The lens isquickly placed on an aluminum weighing pan and the first wet weight, W₁,is measured. Next, the aluminum pan with lens is placed in a oven at 36°C. for a period of at least 24 hours. After heat treating, the pan withlens is removed, placed in a desiccator, and allowed to cool to roomtemperature (about 22° C.). The pan with lens is weighed again todetermine the dry weight, W_(d). The lens is re-equilibrated inphysiological saline solution and a second wet weight W₂ is determinedthereon. The wet weights (W₁ and W₂) are averaged to yield an averagewet weight, W_(W). The bulk water content is determined by the followingequation:

    Percent water content=(W.sub.w -W.sub.d)/W.sub.w ×100

A preferred lens bulk water content, determined by the "Bulk Technique",is less than about 32 weight percent. More preferably, the lens has awater content of about 10 to 30 weight percent, based on the total lensweight. A particularly preferred lens water content is about 15 to about25 weight percent.

F. Ion and Water Permeability

Unexpectedly, it has been determined that the ion permeability throughthe lens correlates well with on-eye movement. As discussed earlier, itis known that on-eye movement of the lens is required to ensure goodtear exchange, and ultimately, to ensure good cornea health. While theinvention is not bound by theory presented herein, it may be useful todiscuss some theory for a better understanding of ways to practice theinvention.

It is theorized that water permeability is an exceptionally importantfeature for an extended-wear lens which includes oxyperm polymers suchas those disclosed herein. Siloxane-containing oxyperm materials tend toadhere strongly to the eye, thereby stopping on-eye movement. Theability to pass water through the lens is believed to allow asiloxane-containing polymeric lens to move on the eye, where themovement occurs via forces exerted by water being squeezed out of thelens. The water permeability of the lens is also believed important inreplenishing lens water content once pressure is removed. Further, thepermeability of ions is believed to be directly proportional to thepermeability of water. Thus, ion permeability is a predictor of on-eyemovement.

However, regardless of whether the water permeability theory is acorrect understanding of the actual on-eye movement phenomenon, it hasbeen unexpectedly found that above a certain threshhold of ionpermeability through a lens, from the inner surface of the lens to theouter, or vice versa, the lens will move on the eye, and below thethreshhold the lens will adhere to the eye. Thus, the present innovativeextended-wear contact lenses provide a balance between the relativelyhigh oxygen permeability (and associated high binding capacity) ofoxyperm materials with the low binding capacity (high on-eye movement)of ionoperm materials. It is believed that this is accomplished byproviding a plurality of continuous ion transmission pathways for ionand water movement through the lens.

It should be noted that ions may move through the lens via these ionpathways by a number of means. For example, ions may diffuse through thelens because of concentration differences from one surface to another.Ions may also be forced through the ion pathways by the mechanicalaction of blinking, with the concomittent compression forces on the lensessentially squeezing water out of the lens. In addition, the chargenature of the surfaces may provide an electromotive force which drivesion permeation through the lens. At times, one of these driving forcesmay be larger than the others, while at other times the relativemagnitude may reverse. This discussion is presented to clarify that theinvention is not restricted by the method or driving force by which ionsmove through the lens.

Neither the measurement of water permeability nor ion permeabilitythrough an ophthalmic lens is considered a routine matter of testing inthe industry. Accordingly, a discussion of the preferred ion or waterpermeability ranges warrants a discussion of the measurement techniquesused to determine the permeability.

The water permeability of a lens may be determined from the rate ofwater permeation through the lens, from one surface to another surface.The water permeability of a lens may be determined by positioning a lensbetween two reservoirs holding solutions having known, and different,initial concentrations of radiolabeled water (e.g., tritiated water),and then measuring concentration of radiolabeled water in the"receiving" reservoir (the reservoir towards which the net flow ofradiolabeled water is positive) as a function of time.

The relative ion permeability of a lens may be determined from the rateof ion permeation through the lens, from one surface to another surface.The rate of ion permeation may be determined by positioning a lensbetween two reservoirs holding solutions having known, and different,initial ion concentrations, and then measuring conductivity in the"receiving" reservoir (the reservoir towards which the net flow of ionsis positive) as a function of time. The concentration of ions, such assodium, can be measured accurately using a pH meter and an ion-selectiveelectrode. Ions are believed to be transmitted through a lens, frominner to outer surfaces and vice versa, primarily by the diffusion ofions through water pathways in the lens. Ion permeability through a lensis believed to be directly proportional to water permeability through alens.

1. Ionoflux Measurement Technique

The following technique, referred to herein as the "Ionoflux Technique",is a preferred method for determining the ion permeability of a lens.This technique may be used to determine the likelihood of adequateon-eye movement.

The "Ionoflux Technique" involves the use of a conductometer (LF 2000/C,catalog no. 300105, Wissenschaftlich-Technische Werkstatten GmbH (WTW),Germany), an electrode equipped with a temperature sensor (LR 01/T,catalog no. 302 520, WTW), a donor chamber containing a salt solution, areceiving chamber containing about 60 ml of deionized water, a stir barand a thermostat.

The donor chamber is specially designed for sealing a contact lensthereto, so that the donor solution does not pass around the lens (i.e.,ions may only pass through the lens). The donor chamber is composed of aglass tube which is threaded at the end which is immersed in thereceiving solution. The glass tube includes a centrally located hole ofabout 9 mm in diameter. A lid, which is threaded to mate with the glasstube, holds a lens-retaining member which includes a centrally locatedhole of about 8 mm in diameter. The lens-retaining member includes amale portion adapted to mate with and seal the edges of the inner(concave) surface of a lens and a female portion adapted to mate withand seal the edges of the outer (convex) surface of a lens.

The lens to be measured is placed in the lens-retaining member, betweenthe male and female portions. The male and female portions includeflexible sealing rings which are positioned between the lens and therespective male or female portion. After positioning the lens in thelens-retaining member, the lens-retaining member is placed in thethreaded lid. The lid is screwed onto the glass tube to define the donorchamber. The donor chamber is filled with 16 ml of 0.1 molar NaClsolution. The receiving chamber is filled with 60 ml of deionized water.The leads of the conductivity meter are immersed in the deionized waterof the receiving chamber and a stir bar is added to the receivingchamber. The receiving chamber is placed in a thermostat and thetemperature is held at about 35° C. Finally, the donor chamber isimmersed in the receiving chamber.

Measurements of conductivity are taken every 20 minutes for about threehours, starting 10 minutes after immersion of the donor chamber into thereceiving chamber. The Ionoflux Diffusion Coefficient, D, is determinedby applying Fick's law as follows:

    D=-n'/(A×dc/dx)

where

n'=rate of ion transport (mol/min)

A=area of lens exposed (mm²)

D=Ionoflux Diffusion Coefficient (mm² /min)

dc=concentration difference (mol/L)

dx=thickness of lens (mm)

An Ionoflux Diffusion Coefficient of greater than about 6.4×10⁻⁶ mm²/min is preferred for achieving sufficient on-eye movement. Morepreferably, the Ionoflux Diffusion Coefficient is greater than about2.6×10⁻⁶ mm² /min, while most preferably, the Ionoflux DiffusionCoefficient is greater than about 1.5×10⁻⁶ mm² /min. It must beemphasized that the Ionoflux Diffusion Coefficient correlates with ionpermeability through the lens, and thereby is a predictor of on-eyemovement.

2. Ionoton Measurement Technique

The following technique, referred to herein as the "Ionoton Technique",is another preferred method for determining the relative ionpermeability of a lens. The technique is based on measurement of thediffusion of sodium chloride through a lens.

The "Ionoton Technique" involves the use of a pH meter (Beckman, VWRcatalog no. BK123142), a VSC-1 Diffusion Cell Drive Console (Crown-Bio,Somerville, N.J.), a DCB-100B Diffusion Cell (Crown-Bio), and a 6 cmsodium ion-specific electrode (Microelectronics, Londonderry, N.H.,catalog no. MI414P). The technique is not limited to the aforementionedinstruments or materials; equivalent instruments or materials may beused.

First, a contact lens is mounted onto an orifice of the DCB-100B cellchamber, the donor chamber. Next, the connecting cell chamber (receptorchamber) is placed against the cell chamber containing the contact lensand tightly clamped on the clamp holder supplied with the VSC-1 DriveConsole. Then, a phosphate-buffered saline (PBS, Mediatech catalog no.21-031-LV) is placed into the receptor side of the cell chamber. Stirbars are added to each cell chamber. The 6 cm electrode is placed intothe PBS saline receptor side. After the electrode has equilibrated inthe PBS saline, the pH meter is placed in the mV function to establishthe 0 mV point. PBS which has been saturated with sodium chloride isadded to the donor chamber.

The millivolt signal is recorded at 5, 10, 15, 30, 60, 120, and 180minute intervals. The millivolt signal is converted to a sodium ionconcentration by a standard curve of sodium ion concentration vs.millivolt signal. The Ionoton Ion Permeability Coefficient, P, is thendetermined in accordance with the following equation:

    ln (1-2C(t)/C(0))=-2APt/Vd

where:

C(t)=concentration of sodium ions at time t in the receiving cell

C(0)=initial concentration of sodium ions in donor cell

A=membrane areas i.e., lens area exposed to cells

V=volume of cell compartment (3.0 ml)

d=average lens thickness in the area exposed

P=permeability coefficient

The average thickness of the lens in the exposed test area may bedetermined by averaging a number of readings, e.g., 10 readings, with alow-pressure thickness-measuring instrument, such as a Mitotoyamicrometer VL-50, or equivalents thereof. The Ionoton Ion PermeabilityCoefficient, P, having units of cm² /second, may be determined from theslope of a plot of time (t) v. In(1-2 C(t)/C(0))×(-2At/Vd).

An Ionoton Ion Permeability Coefficient, P, of greater than about0.2×10⁻⁶ cm² /sec is preferred, while greater than about 0.3×10⁻⁶ cm²/sec is more preferred and greater than about 0.4×10⁻⁶ cm² /sec is mostpreferred. It must be emphasized that the Ionoton Ion PermeabilityCoefficient correlates with ion permeability through the lens, andthereby is a predictor of on-eye movement.

3. Hydrodell Water Permeability Technique

The following technique, referred to herein as the "HydrodellTechnique", is a preferred method for determining the water permeabilityof a lens. This technique may be used to determine the likelihood ofadequate on-eye movement.

The Hydrodell Technique involves the measurement of the rate of transferof the radiolabeled solutes THO (³ H--HO or tritiated water) and ¹⁴C-glucose across the contact lens using a two-chamber apparatus. ¹⁴C-glucose is used in this measurement technique to reveal any leak inthe system during testing. The lens is mounted between chambers, whichare stirred at a controllable rate. Chamber I contains a solution with ahigh concentration of labeled solute. Chamber II, the "receivingchamber", contains an identical solution but without the labeled solute.Samples of the solution in chambers I and II are taken at intervals overthe test period. The radioactivity in the samples is measured. Thepermeability of the lens is calculated from the measured radioactivity,the sample times, the chamber volumes and the lens area exposed to thesolutions. A more detailed description of the Hydrodell Techniquefollows.

a. Solution Preparation

Dulbecco's phosphate buffered saline (DPBS) is prepared by firstdissolving, sequentially, about 160 g sodium chloride (NaCl), about 4grams potassium chloride (KCl), about 23 grams disodium hydrogenorthophosphate (Na₂ HPO₄), about 4 grams potassium dihydrogenorthophosphate (KH₂ PO₄), and about 10 grams sodium azide in a liter ofreverse-osmosis (MilliQ) water. Then, the pH is adjusted to about 7.3 byadding appropriate amounts of HCl. Finally, the buffer solution isdiluted to 1:20 (50 ml buffer solution with 950 ml reverse-osmosiswater), and allowed to degas either in a screw capped containerovernight or under vacuum.

A Cold Glucose buffer solution is prepared by adding about 0.1 gramsD-glucose to one liter of DPBS, followed by sterilization via filtrationthrough a 0.2 μl millipore filter and storage at 4° C. until use.

The Chamber I solution is prepared by adding about 6 μl THO (TR53, 1.0mCi/ml activity, available from Amersham Australia, located in NorthRyde NSW Australia) and about 16 μ¹⁴ C-glucose (in ethanol, availablefrom Amersham Australia) to about 12 ml of the Cold Glucose buffersolution. Preferably, this solution is used within about 24 hours ofpreparation. The Chamber II solution is DPBS.

b. Apparatus Preparation

The chambers have a volume sufficient to hold about 12 ml of solutionduring testing. While the exact shape of the chambers is not critical,both chambers have rectangular cross-sections for ease of construction.The chambers may be made from a variety of water-proof rigid materials,preferably clear (e.g., acrylic plates, FX Plastics, Marrickville NSWAustralia) so that samples may be observed during testing. Each chamberhas a circular aperture of about 7 mm diameter appropriate for mountinga lens between the chambers for contact with solutions held within thechambers. Some affixing means, such as a set of mounting bolts, arenecessary to securely affix one chamber to the other with the lensmounted in between.

A test contact lens is mounted symmetrically over the aperture ofChamber II. Folds and wrinkles are manually removed from the lens.Chamber I is positioned adjacent the aperture and mounted lens ofChamber II, and the chambers are secured to one another using mountingbolts.

About 12 ml (V2) of DPBS is placed in Chamber II. About 12 ml of theChamber I labeled solution is placed in Chamber I, at which point timet=0 is established. Stirrers are added to both chambers and the stirrerspeed is set at about 1200 rpm.

c. Sampling

Sampling generally starts at time t₀ =5 minutes. The final sample time,t_(f), is usually at about 50 minutes for high water content lenses andabout 120 minutes for low water content lenses, although these times arenot critical.

At time t₀ =5 minutes, two samples of about 0.2 ml volume are pipettedfrom Chamber I, and two 0.2 ml aliquots of DPBS are added to Chamber Ito restore the volume. These samples are placed into plastic countingtubes with about 4 ml Ultima Gold™ cocktail (available from PackardInstrument Co., Meriden, Conn.) and about 0.9 ml DPBS.

Also at time t₀, one sample of about 1.0 ml volume is pipetted fromChamber II and one 1.0 ml aliquot of DPBS is added to Chamber II torestore the volume. The sample is placed into a plastic counting tubewith about 4 ml Ultima Gold™ cocktail.

At intermediate times between t₀ and t_(f) (e.g., every 10 minutes), onesample of about 1.0 ml volume is pipetted from Chamber II and one 1.0 mlaliquot of DPBS is added to Chamber II to restore the volume. Eachsample is placed into a plastic counting tube with about 4 ml UltimaGold™ cocktail.

At time t_(f), two samples of about 0.2 ml volume are pipetted fromChamber I. These samples are placed into plastic counting tubes withabout 4 ml Ultima Gold™ cocktail and about 0.9 ml DPBS.

Also at time t_(f), two samples of about 1.0 ml volume are pipetted fromChamber II. These samples are placed into plastic counting tubes withabout 4 ml Ultima Golds™ cocktail.

d. Measurements

The activity of the samples are measured by liquid scintillationcounting, or other appropriate technique. Liquid scintillation countingmay be advantageously accomplished by using protocol number 6 for ³ H/¹⁴C on a Tri-Carb Liquid Scintillation Analyzer (1900TR, available fromPackard Instrument Co.).

Three standards containing about 10⁴ to 10⁵ cpm THO in reversed-osmosis(MilliQ) water are prepared. Three standards containing about 10⁴ to 10⁵cpm ¹⁴ C glucose in reversed-osmosis (MilliQ) water are also prepared. Ablank containing MilliQ water is prepared.

The scintillation analyzer settings are LLA=0 KeV and ULA=12 KeV for ³ H("1") in channel 1 and LLB=12 KeV and ULB=156 KeV for ¹⁴ C ("2") inchannel 2. The standards and blank are counted three times during eachcounting of samples, and the counts are averaged. The following denotethe relevant measured sample activities:

b₁ =measured activity of blank sample in channel 1

b₂ =measured activity of blank sample in channel 2

S'₁₁ =measured activity of standard ³ H sample in channel 1

S'₁₂ =measured activity of standard ¹⁴ C sample in channel 2

S'₂₁ =measured activity of standard ³ H sample in channel 1

S'₂₂ =measured activity of standard ¹⁴ C sample in channel 2

y₁ =measured activity of test sample (both ³ H and ¹⁴ C) in channel 1

y₂ =measured activity of test sample (both ³ H and ¹⁴ C) in channel 2

e. Water Permeability Calculation

In order to calculate the actual activity of a sample, the measuredactivities of the isotopes, ³ H and ¹⁴ C, must first be corrected toremove the cross-contamination error due to the presence of bothisotopes in one sample. Without explaining the mathematical derivations,the following stepwise procedure is offered as an example of one methodof determining water permeability from the above measurements:

(1) Calculate S₁₁, S₁₂, S₂₁, and S₂₂, from the following equations:

    S.sub.11 =S'.sub.11 -b.sub.1

    S.sub.12 =S'.sub.12 -b.sub.1

    S.sub.21 =S'.sub.21 -b.sub.2

    S.sub.22 =S'.sub.22 -b.sub.2

(2) Calculate a₁₂ and a₂₁ from the following equations:

    a.sub.12 =S.sub.12 /S.sub.22

    a.sub.21 =S.sub.21 /S.sub.11

(3) Calculate corrected concentrations of ³ H ("1") and ¹⁴ C ("2") fromthe following equations:

    c.sub.1 = (y.sub.1 -b.sub.1)-a.sub.12 (y.sub.2 -b.sub.2)!/(1-a.sub.12 a.sub.21)V

    c.sub.2 = (y.sub.2 -b.sub.2)-a.sub.21 (y.sub.1 -b.sub.1)!/(1-a.sub.12 a.sub.21)V

where V is the volume of the test sample.

(4) Calculate water permeability for an interval from t₁ to t₂ asfollows:

    P=V.sub.II  c.sub.II (t.sub.2)-c.sub.II (t.sub.1)!/A(c.sub.I -c.sub.II)(t.sub.1 -t.sub.2)

where V_(II) is the volume of Chamber II, c_(II) (t₂) is theconcentration of ³ H in Chamber II at time t₂, c_(II) (t₁) is theconcentration of ³ H in Chamber II at time t₁, A is the area of lensexposure, c_(I) is the average concentration of ³ H in Chamber I overthe time period t₁ to t₂ and c_(II) is the average concentration of ³ Hin Chamber II over the time period t₁ to t₂.

The ophthalmic lenses of one embodiment of the present invention have aHydrodell Water Permeability Coefficient of greater than about 0.2×10⁻⁶cm² /sec. The ophthalmic lenses in a preferred embodiment of theinvention have Hydrodell Water Permeability Coefficient of greater thanabout 0.3×10⁻⁶ cm² /sec. The ophthalmic lenses in a preferred embodimentof the invention have Hydrodell Water Permeability Coefficient ofgreater than about 0.4×10⁻⁶ cm² /sec.

G. Oxygen Transmissibility and Permeability

As mentioned earlier, the cornea receives oxygen primarily from thecornea surface which is exposed to the environment, in contrast to othertissues which receives oxygen from blood flow. Thus, an ophthalmic lenswhich may be worn on the eye for extended periods of time must allowsufficient oxygen to permeate through the lens to the cornea to sustaincorneal health. One result of the cornea receiving an inadequate amountof oxygen is that the cornea will swell. In a preferred embodiment, theoxygen transmissibility of the present ophthalmic lenses is sufficientto prevent any clinically significant amount of corneal swelling fromoccurring.

A preferred ophthalmic lens material will have an oxygentransmissibility, Dk/t, of at least 70 (cm³ oxygen)(mm)/mm-cm² ×(sec/mmHg)×10⁻⁹ or (barrers/mm), more preferably at least 75 barrers/mm, andmost preferably at least 87 barrers/mm.

The oxygen permeability of a lens and oxygen transmissibility of a lensmaterial may be determined by the following technique. Oxygen fluxes (J)are measured at 34 C in a wet cell (i.e., gas streams are maintained atabout 100% relative humidity) using a Dk1000 instrument (available fromApplied Design and Development Co., Norcross, Ga.), or similaranalytical instrument. An air stream, having a known percentage ofoxygen (e.g., 21%), is passed across one side of the lens at a rate ofabout 10 to 20 cm³ /min., while a nitrogen stream is passed on theopposite side of the lens at a rate of about 10 to 20 cm³ /min. Thebarometric pressure surrounding the system, P_(measured), is measured.The thickness (t) of the lens in the area being exposed for testing isdetermined by measuring about 10 locations with a Mitotoya micrometerVL-50, or similar instrument, and averaging the measurements. The oxygenconcentration in the nitrogen stream (i.e., oxygen which diffusesthrough the lens) is measured using the DK1000 instrument. The oxygenpermeability of the lens material, D_(k), is determined from thefollowing formula:

    D.sub.k =Jt/(P.sub.oxygen)

where

J=oxygen flux (microliters O₂ /cm² -minute)

P_(oxygen) =(P_(measured) -P_(water) vapor)×(% O₂ in air stream) (mmHg)=partial pressure of oxygen in the air stream

P_(measured) =barometric pressure (mm Hg)

P_(water) vapor =0 mm Hg at 34 C (in a dry cell) (mm Hg)

P_(water) vapor =40 mm Hg at 34 C (in a wet cell) (mm Hg)

t=average thickness of the lens over the exposed test area (mm)

where D_(k) is expressed in units of barrers, i.e., ((ccoxygen)(mm)/cm²)×(sec/mm Hg)×10⁻¹⁰.

The oxygen transmissibility (D_(k) /t) of the material may be calculatedby dividing the oxygen permeability (D_(k)) by the average thickness (t)of the lens.

H. Mechanical On-eye Movement Parameters

On-eye movement of a lens may be predicted from the mechanicalproperties of a lens, the ion or water permeability through the lens, orboth the mechanical properties and ion or water permeability. In fact,on-eye movement may be predicted more accurately from a combination ofmechanical properties and ion or water permeability.

1. Tensile Modulus and Short Relaxation Time

Tensile mechanical testing may be performed on lens materials todetermine mechanical properties. A procedure for preparing a test samplefrom a lens for subsequent mechanical testing includes the followingsteps:

1. Cut a parallel-sided strip through the center of the lens. A suitablewidth for the strip is about 3.1 mm.

2. Immerse the test strip in a phosphate-buffered saline solution(approximating ocular fluid osmolality) for a period of about 24 hoursbefore testing.

3. Conduct mechanical testing with the test strip immersed inphosphate-buffered saline at ambient temperature (about 23° C.).

Tensile modulus may be measured by applying a stain rate of about 100%per minute to the test strip and recording the resultant stress.However, the procedure may be used at differing strain rates.

Stress relaxation is measured by applying a constant strain of about 5%to the test strip and recording the resultant stress for about 5minutes. A useful mechanical testing instrument for this type of testingis the Vitrodyne V-200 from Liveco Biomechanical Instruments, located inBurlington, Vt.

In order to analyze stress relaxation data, a three elementMaxwell-Wiechert model (a spring and two spring-dashpot elements inparallel) may be assumed for the polymer material. For this model thestress relaxation modulus is given by the following equation:

    E(t)=E.sub.0 +E.sub.1 exp (-t/t.sub.1)+E.sub.2 exp (-t/t.sub.2)

Stress v. time curves may be normalized to the maximum (initial) stressinduced in the samples. These curves may be analyzed by a variety ofcommercially available software (for example, ORIGIN software) byfitting the double exponential equation:

    y(t)=y.sub.0 +A.sub.1 exp (-t/t.sub.1)+A.sub.2 exp (-t/t.sub.2)

in order to obtain the stress relaxation parameters y₀, t₁, A₁, t₂, andA₂.

It has been determined that the tensile modulus (modulus of elasticity,E) and the short relaxation time constant (t₁) correlate well withon-eye movement. In order to have appropriate on-eye movement, a lenspreferably has a tensile modulus of less than about 3 MPa Morepreferably, E is about 0.4 to about 2.5 MPa while a particularlypreferred E is about 0.5 to about 1.5 MPa.

A preferred short relaxation time constant (t₁) is greater than about3.5 seconds. More preferably, t₁ is greater than about 4 seconds, whilea particularly preferred t₁ is greater than about 4.5 seconds.

2. Tangent Delta

Lenses may also be evaluated by dynamic mechanical analysis (DMA)methods. It has been determined that a factor known as tan δ (i.e.,tangent delta), also known as mechanical loss factor, correlates wellwith on-eye movement. It has been observed that lens materials whichmove on the eye exhibit a distinct increase in tan δ with increasingfrequency from about 0.1 to 10 Hz when these materials are tested bydynamic mechanical analysis. The tan δ of a preferred lens material isabove about 0.2 at 0.1 Hz and increases to about 0.25 or more at about10 Hz. A tan δ of about 0.3 or greater at 10 Hz is more preferred, whilea tan δ of about 0.5 or greater at 10 Hz is even more preferred.

DMA measurements may be determined in accordance with the followingprocedure. A disk of lens material having a diameter of about 3.0 mm anda thickness of about 0.50 mm is formed. The disk is placed in aPerkin-Elmer DMA-7 instrument. The disk is immersed in a solutionbuffered to a pH of about 7.2 and held isothermally for a period ofabout 10 minutes or more prior to testing, at a temperature of about 23°to 35° C. The instrument is set to a compression measuring mode and thestrain on the sample is adjusted to about 2% to 4%, depending on thesample response. The amplitude of compression is about 2 to 4 μm.Measurements of the modulus of elasticity and tan δ are taken atfrequencies of about 0.1, about 1, and about 10 Hz.

3. Parameter Combinations

In order to assure appropriate movement of the lens on the eye, one mayselect materials which have a combination of the above-discussedproperties. Therefore, a preferred group of extended-wear contact lensmaterials have (a) a modulus of elasticity (E) of about 1.5 MPa or less,(b) a short time relaxation constant (t₁) of greater than about 4seconds, and (c) an Ionoton Ion Permeability Coefficient of greater thanabout 0.3×10⁻⁶ cm² /sec and/or an Ionoflux Diffusion Coefficient greaterthan about 6.4×10⁻⁶ mm² /min.

I. Examples of Suitable Materials

1. Material "A"

One embodiment of a suitable core material of the present ophthalmiclenses is a copolymer formed from the following monomeric and macromericcomponents:

(a) about 5 to about 94 dry weight percent of a macromer having thesegment of the formula

    CP-PAO-DU-ALK-PDMS-ALK-DU-PAO-CP

where

PDMS is a divalent poly(disubstituted siloxane),

ALK is an alkylene or alkylenoxy group having at least 3 carbon atoms,

DU is a diurethane-containing group,

PAO is a divalent polyoxyalkylene, and

CP is selected from acrylates and methacrylates,

wherein said macromer has a number-average molecular weight of 2000 to10,000;

(b) about 5 to about 60 weight percentmethacryloxypropyltris(trimethylsiloxy)silane;

(c) about 1 to about 30 weight percent of an acrylate or methacrylatemonomer; and

(d) 0 to 5 weight percent cross-linking agent,

with the weight percentages being based upon the dry weight of thepolymer components.

A preferred polysiloxane macromer segment is defined by the formula

    CP-PAO-DU-ALK-PDMS-ALK-DU-PAO-CP

where

PDMS is a divalent poly(disubstituted siloxane);

CP is an isocyanatoalkyl acrylate or methacylate, preferablyisocyanatoethyl methacrylate, where the urethane group is bonded to theterminal carbon on the PAO group;

PAO is a divalent polyoxyalkylene (which may be substituted), and ispreferably a polyethylene oxide, i.e., (--CH₂ --CH₂ --O--)_(m) CH₂ CH₂-- where m may range from about 3 to about 44, more preferably about 4to about 24;

DU is a diurethane, preferably including a cyclic structure,

where an oxygen of the urethane linkage (1) is bonded to the PAO groupand an oxygen of the urethane linkage (2) is bonded to the ALK group;

and ALK is an alkylene or alkylenoxy group having at least 3 carbonatoms, preferably a branched alkylene group or an alkylenoxy grouphaving 3 to 6 carbon atoms, and most preferably a sec-butyl (i.e., --CH₂CH₂ CH(CH₃)--) group or an ethoxypropoxy group (e.g., --O--(CH₂)₂--O--(CH₂)₃ --).

It will be noted that the DU group can be formed from a wide variety ofdiisocyanates or triisocyanates, including aliphatic, cycloaliphatic oraromatic polyisocyanates. These isocyanates include, without limitationthereto, ethylene diisocyanate; 1,2-diisocyanatopropane;1,3-diisocyanatopropane; 1,6-diisocyanatohexane;1,2-diisocyanatocyclohexane; 1,3-diisocyanatocyclohexane;1,4-diisocyanatobenzene, bis(4-isocyanatocyclohexyl)methane;bis(4-isocyanatocyclohexyl)methane; bis(4-isocyanatophenyl)methane; 1,2-and 1,4-toluene diisocyanate; 3,3-dichloro-4,4'-diisocyanatobiphenyl;tris(4-isocyanatophenyl)methane; 1,5-diisocyanatonaphthalene;hydrogenated toluene diisocyanate; 1-isocyanatomethyl-5-isocyanato-1,3,3-trimethylcyclohexane (i.e.,isophorone diisocyanate); 1,3,5-tris(6-isocyanatohexyl)biuret;1,6-diisocyanato-2,2,4-(2,4,4)-trimethylhexane; 2,2'-diisocyanatodiethylfumarate; 1,5-diisocyanato-1-carboxypentane; 1,2-, 1,3-, 1,6-, 1,7-,1,8-, 2,7- and 2,3-diisocyanatonaphthalene; 2,4- and2,7-diisocyanato-1-methylnaphthalene; 1,4-diisocyanatomethylcyclohexane;1,3-diisocyanato-6(7)-methylnaphthalene; 4,4'-diisocyanatobiphenyl;4,4'-diisocyanato-3,3'-dimethoxybisphenyl; 3,3'- and4,4'-diisocyanato-2,2'-dimethylbisphenyl; bis(4-isocyanatophenyl)ethane;bis(4-isocyanatophenyl ether); 1,2- or 1,4-toluene diisocyanate; andmixtures thereof. Preferably DU is formed from isophorone diisocyanateor toluene diisocyanate, and more preferably, isophorone diisocyanate,where one isomeric diurethane structure of isophorone diisocyanate isdefined above.

A preferred Material A macromer segment has the following formula:##STR1## wherein: R₁ and R₂ are lower alkyl (C₁ -C₆), preferably C₁ -C₃alkyl, more preferably methyl;

R₃, R₄, R₅, and R₆ are lower alkylene (C₁ -C₆), preferably C₁ -C₃alkylene, more preferably C₂ -C₃ alkylene, and preferably, where thetotal number of carbon atoms in R₃ and R₅, or R₄ and R₆ is greater than4;

R₇ and R₈ are linear or branched alkylene or an bivalent cycloalkylene,preferably bivalent cycloalkylene;

R₉, R₁₀, R₁₁, and R₁₂ are C₁ -C₂ alkylene, preferably C₂ alkylene;

R₁₃ and R₁₄ are lower alkylene (C₁ -C₆), preferably C₁ -C₃ alkylene,more preferably ethylene; and

R₁₅ and R₁₆ are linear or branched lower alkenylene, preferably C₂ -C₃alkenylene;

m and p, independently of one another, may range from about 3 to about44, more preferably about 4 to about 24; and

n may range from about 13 to about 80, more preferably, about 20 toabout 50, and even more preferably about 24 to about 30.

The polysiloxane macromer may be synthesized by the following preferredprocess. At about room temperature (about 20°-25 C.),poly(dimethylsiloxane)dialkanol having hydroxyalkyl (e.g.,hydroxy-sec-butyl) or hydroxyalkoxy (e.g., hydroxyethylpropoxy) endgroups and having a molecular weight of about 2000 to 3000 preferablyabout 2200, i.e., having about 28 repeating siloxane groups) is reactedwith isophorone diisocyanate at about a 1:2 molar ratio, using about 0.2weight percent (based on polydimethylsiloxane)dibutyltin dilaurate addedas a catalyst The reaction is carried out for about 36 to 60 hours. Tothis mixture is added poly(ethylene glycol) having a molecular weight ofabout 400 to 1200 (more preferably about 500 to 700) at about a 2:1 or2.1:1 molar ratio with respect to the PDMS, about 0.4 to 0.5 weightpercent dibutyltin dilaurate (based on polyethylene glycol weight), andchloroform sufficient to ensure substantial mixture homogeneity. Themixture is agitated for about 12 to 18 hours, then held at a temperatureof about 44° to 48° C. for about 6 to 10 hours. Excess chloroform isevaporated therefrom at about room temperature to produce a compositionhaving about 50 weight percent solids. Then, isocyanatoethylmethacrylate is added to the mixture in about a 2:1 to 2.3:1 molar ratiowith respect to PDMS. The mixture is agitated at room temperature forabout 15 to 20 hours. The resulting solution contains a polysiloxanemacromer having the composition described above and a number-averagemolecular weight of about 2000 to 10,000, more preferably about 3000 to5000.

An advantageous polymeric material formed from the Material A macromerof the present invention is a copolymer of the aforementioned Material Amacromer; an acrylated or methacrylated siloxane monomer, preferablymethacryloxypropyltris (trimethylsiloxy)silane (referred to herein as"Tris"); a hydrophilic monomer, preferably 2-hydroxyethyl methacrylate(HEMA); and preferably, a cross-lining agent such as ethylene glycoldimethacrylate (EGDMA). The final copolymer composition includes about10 to 90, preferably 70 to 90, weight percent polysiloxane macromer;about 5 to 60, preferably about 8 to 20, weight percent siloxanemonomer; about 1 to 30, preferably about 1 to 5, weight percent acrylateor methacrylate monomer; and 0 to about 5, preferably up to about 2weight percent cross-linking agent (e.g., EGDMA) based on a total drycopolymer weight. A more preferred composition includes about 80 to 84polysiloxane macromer, about 12 to 15 weight percent TRIS, about 3 toabout 4 weight percent 2-hydroxyethyl methacrylate, and about 0.7 toabout 1.2 weight percent ethylene glycol dimethacrylate.

The advantageous copolymers of the present invention may be formed fromthe previously-described polysiloxane macromer in the following manner.A monomeric solution is formed by adding Tris, HEMA, DAROCUR® 1173 (aphotoinitator available from Ciba-Geigy Corporation), and optionally,EGDMA to the polysiloxane macromer solution. The resulting polymerprecursor solution preferably contains about 83 to about 95 weightpercent polysiloxane macromer solution, about 5 to about 10 weightpercent Tris, about 0.5 to about 5 weight percent HEMA, about 0.1 toabout 1.0 weight percent DAROCUR® 1173, and about 0.1 to about 1.0weight percent EGDMA. More preferably, the monomer solution containsabout 87 to about 93 weight percent polysiloxane macromer solution,about 7 to about 8 weight percent Tris, about 2 to about 4 weightpercent HEMA, about 0.3 to about 0.7 weight percent DAROCUR® 1173, andabout 0.3 to about 0.7 weight percent EGDMA. The monomer solution ispreferably agitated for about 8 to about 24 hours prior to thepolymerization step.

Contact lenses may be prepared from the monomer solution by applying themonomer solution to appropriate lens molds and applying sufficientultraviolet (UV) radiation to initiate polymerization. The ultravioletlight may be applied for a period of a few minutes to about 5 hours,depending on the intensity of light applied. Subsequent topolymerization, the contact lens may be extracted with a solvent, e.g.,isopropanol, to remove unreacted monomers.

Thus, generally, one embodiment of the present invention is a method offorming a molded polymeric article suitable for ophthalmic applications(especially a contact lens), including the following steps:

(a) contacting a poly(dialkylsiloxane)dialkanol with a diisocyanatecompound in the presence of a first catalyst at conditions sufficient tocause reaction of said dialkanol with said diisocyanate, thereby forminga first mixture;

(b) contacting said first mixture with poly(alkylene glycol), a secondcatalyst, and sufficient solvent to ensure mixture homogeneity, therebyforming a second mixture;

(c) evaporating sufficient solvent from said second mixture to generatea third mixture having a solids content of about 40 to 60 weightpercent;

(d) adding isocyanatoalkyl methacrylate to said third mixture, therebyforming a fourth mixture containing a polysiloxane macromer;

(e) adding to said fourth mixture3-methacryloxypropyltris(trimethylsiloxy)silane (TRIS), a hydrophilicmonomer, a cross-linking agent and a photoinitiator, thereby forming afifth mixture;

(f) placing said fifth mixture into a mold; and

(g) applying sufficient radiation to copolymerize said monomers, therebyforming said polymeric material into a molded polymeric article.

The hydrophilic copolymers of the present invention are especiallyadvantageous in the formation of "soft" contact lenses. In the use ofthe copolymers in the contact lens field, the lenses have a watercontent of about 10 to about 50 weight percent, more preferably about 10to about 30 weight percent, and most preferably about 15 to about 22weight percent, based on total hydrophilic polymer weight. Preferably,the fully-hydrated contact lens has an oxygen transmissibility (D_(k)/t) of greater than 70 barrers/mm (i.e., (cc oxygen)(mm)/cm² !× sec/mmHg!×10⁻¹⁰), more preferably greater than about 75 barrers/mm, and mostpreferably greater than about 87 barrers/mm.

2. Material "B" Polysiloxane-comprising perfluoroalkyl ethers

The Material "B" macromer is defined by formula (I):

    P.sub.1 --(Y).sub.m --(L--X.sub.1)p--Q--(X.sub.1 --L).sub.p --(Y).sub.m --P.sub.1                                                 (I)

where

each P1, independently of the others, is a free-radical-polymerizablegroup;

each Y, independently of the others, is --CONHCOO--, --CONHCONH--,--OCONHCO--, --NHCONHCO--, --NHCO--, --CONH--, --NHCONH--, --COO--,--OCO--, --NHCOO-- or --OCONH--;

m and p, independently of one another, are 0 or 1;

each L, independently of the others, is a divalent radical of an organiccompound having up to 20 carbon atoms;

each X₁, independently of the others, is --NHCO--, --CONH--, --NHCONH--,--COO--, --OCO--, --NHCOO-- or --OCONH--; and

Q is a bivalent polymer fragment consisting of the segments:

(a) --(E)_(k) --Z--CF₂ --(OCF₂)_(x) --(OCF₂ CF₂)_(y) --OCF₂ --Z--(E)_(k)--,

where x+y is a number in the range of 10 to 30;

each Z, independently of the others, is a divalent radical having up to12 carbon atoms or Z is a bond;

each E, independently of the others, is --(OCH₂ CH₂)_(q) --, where q hasa value of from 0 to 2, and where the link --Z--E-- represents thesequence --Z--(OCH₂ CH₂)_(q) --; and

k is 0 or 1; ##STR2## where n is an integer from 5 to 100; Alk isalkylene having up to 20 carbon atoms;

80-100% of the radicals R₁, R₂, R₃ and R₄, independently of one another,are alkyl and 0-20% of the radicals R₁, R₂, R₃ and R₄, independently ofone another, are alkenyl, aryl or cyanoalkyl; and

(c) X₂ --R--X₂,

where R is a divalent organic radical having up to 20 carbon atoms, and

each X₂, independently of the others, is --NHCO--, --CONH--, --NHCONH--,--COO--, --OCO--, --NHCOO-- or OCONH--;

with the provisos that there must be at least one of each segment (a),(b), and (c) in Q, that each segment (a) or (b) has a segment (c)attached to it, and that each segment (c) has a segment (a) or (b)attached to it.

The number of segments (b) in the polymer fragment Q is preferablygreater than or equal to the number of segments (a). The ratio betweenthe number of segments (a) and (b) in the polymer fragment Q ispreferably 3:4, 2:3, 1:2 or 1:1. The molar ratio between the number ofsegments (a) and (b) in the polymer fragment Q is more preferably 2:3,1:2 or 1:1.

The mean molecular weight of the polymer fragment Q is in the range ofabout 1000 to about 20000, preferably in the range of about 3000 toabout 15000, particularly preferably in the range of about 5000 to about12000.

The total number of segments (a) and (b) in the polymer fragment Q ispreferably in the range of 2 to about 11, particularly preferably in therange of 2 to about 9, and in particular in the range of 2 to about 7.The smallest polymer unit Q is preferably composed of one perfluorosegment (a), one siloxane segment (b) and one segment (c).

In a preferred embodiment of the polymer fragment Q, which preferablyhas a composition in the abovementioned ratios, the polymer fragment Qis terminated at each end by a siloxane segment (b).

The compositions in a bivalent polymer fragment Q always correspondabove and below to a mean statistical composition. This means that, forexample, even individual block copolymer radicals containing identicalrecurring units are included, so long as the final mean statisticalcomposition is as specified.

X₁ is preferably --NHCONH--, --NHCOO-- or --OCONH--, particularlypreferably --NHCOO-- or --OCONH--.

The X₂ --R--X₂ segment is preferably a radical derived from adiisocyanate, where each X₂, independently of the other, is NHCONH--,--NHCOO-- or --OCONH--, in particular --NHCOO-- or --OCONH--.

Z is preferably a bond, lower alkylene or --CONH-arylene, in which the--CO--moiety is linked to a CF₂ group. Z is particularly preferablylower alkylene, in particular methylene.

q is preferably 0, 1, 1.5 or 2, particularly preferably 0 or 1.5.

The perfluoroalkoxy units OCF₂ and OCF₂ CF₂ with the indices x and y insegment (a) can either have a random distribution or be in the form ofblocks in a chain. The sum of the indices x+y is preferably a number inthe range of 10 to 25, particularly preferably of 10 to 15. The ratiox:y is preferably in the range of 0.5 to 1.5, in particular in the rangeof 0.7 to 1.1.

A free-radical-polymerizable group P₁ is, for example, alkenylalkenylaryl or alkenylarylenealkyl having up to 20 carbon atoms.Examples of alkenyl are vinyl, allyl, 1-propen-2-yl, 1-buten-2-, -3- and4-yl, 2-buten-3-yl, and the isomers of pentenyl, hexenyl, octenyl,decenyl and undecenyl. Examples of alkenylaryl are vinylphenyl,vinylnaphthyl or allylphenyl. An example of alkenylarylenealkyl is o-,m-, or p-vinylbenzyl.

P₁ is preferably alkenyl or alkenylaryl having up to 12 carbon atoms,particularly preferably alkenyl having up to 8 carbon atoms, inparticular alkenyl having up to 4 carbon atoms.

Y is preferably --COO--, --OCO--, --NHCONH--, --NHCOO--, --OCONH--,NHCO-- or --CONH--, particularly preferably --COO--, --OCO--, NHCO-- or--CONH--, and in particular, --COO-- or --OCO--.

In a preferred embodiment, the indices, m and p, are not simultaneouslyzero. If p is zero, m is preferably 1.

L is preferably alkylene, arylene, a saturated bivalent cycloaliphaticgroup having 6 to 20 carbon atoms, arylenealkylene, alkylenearylene,alkylenearylenealkylene or arylenealkylenearylene.

Preferably, L is a divalent radical having up to 12 carbon atoms,particularly preferably a divalent radical having up to 8 carbon atoms.In a preferred embodiment, L is furthermore alkylene or arylene havingup to 12 carbon atoms. A particularly preferred embodiment of L is loweralkylene, in particular lower alkylene having up to 4 carbon atoms.

The divalent radical R is, for example, alkylene, arylene,alkylenearylene, arylenealkylene or arylenealkylenearylene having up to20 carbon atoms, a saturated bivalent cycloaliphatic group having 6 to20 carbon atoms or cycloalkylenealkylenecycloalkylene having 7 to 20carbon atoms.

In a preferred embodiment, R is alkylene, arylene, alkylenearylene,arylenealkylene or arylenealkylenearylene having up to 14 carbon atomsor a saturated divalent cycloaliphatic group having 6 to 14 carbonatoms. In a particularly preferred embodiment, R is alkylene or arylenehaving up to 12 carbon atoms or a saturated bivalent cycloaliphaticgroup having 6 to 14 carbon atoms.

In a preferred embodiment, R is alkylene or arylene having up to 10carbon atoms or a saturated bivalent cycloaliphatic group having 6 to 10carbon atoms.

In a particularly preferred meaning, R is a radical derived from adiisocyanate, for example from hexane 1,6diisocyanate,2,2,4-trimethylhexane 1,6-diisocyanate, tetramethylene diisocyanate,phenylene 1,4diisocyanate, toluene 2,4-diisocyanate, toluene2,6diisocyanate, m- or p-tetramethylxylene diisocyanate, isophoronediisocyanate or cyclohexane 1,4-diisocyanate.

In a preferred meaning, n is an integer from 5 to 70, particularlypreferably 10 to 50, in particular 14 to 28.

In a preferred meaning, 80-100%, preferably 85-100%, in particular90-100%, of the radicals R₁, R₂, R₃ and R₄ are, independently of oneanother, lower alkyl having up to 8 carbon atoms, particularlypreferably lower alkyl having up to 4carbon atoms, especially loweralkyl having up to 2 carbon atoms. A further particularly preferredembodiment of R₁, R₂, R₃ and R₄ is methyl.

In a preferred meaning, 0-20%, preferably 0-15%, in particular 0-10%, ofthe radicals R₁, R₂, R₃ and R₄ are, independently of one another, loweralkenyl, unsubstituted or lower alkyl- or lower alkoxy-substitutedphenyl or cyano(lower alkyl).

Arylene is preferably phenylene or naphthylene, which is unsubstitutedor substituted by lower alkyl or lower alkoxy, in particular1,3-phenylene, 1,4-phenylene or methyl-1,4-phenylene, 1,5-naphthylene or1,8-naphthylene.

Aryl is a carbocyclic aromatic radical which is unsubstituted orsubstituted preferably by lower alkyl or lower alkoxy. Examples arephenyl, tolyl, xylyl, methoxyphenyl, t-butoxyphenyl, naphthyl andphenanthryl.

A saturated bivalent cycloaliphatic group is preferably cycloalkylene,for example cyclohexylene or cyclohexylene(lower alkylene), for examplecyclohexylenemethylene, which is unsubstituted or substituted by one ormore lower alkyl groups, for example methyl groups, for exampletrimethylcyclohexylenemethylene, for example the bivalent isophoroneradical.

For the purposes of the present invention, the term "lower" inconnection with radicals and compounds, unless defined otherwise,denotes, in particular, radicals or compounds having up to 8 carbonatoms, preferably having up to 4 carbon atoms.

Lower alkyl has, in particular, up to 8 carbon atoms, preferably up to 4carbon atoms, and is, for example, methyl, ethyl, propyl, butyl,tert-butyl, pentyl, hexyl or isohexyl.

Alkylene has up to 12 carbon atoms and can be straight-chain orbranched. Suitable examples are decylene, octylene, hexylene, pentylene,butylene, propylene, ethylene, methylene, 2-propylene, 2-butylene,3-pentylene, and the like.

Lower alkylene is alkylene having up to 8 carbon atoms, particularlypreferably up to 4 carbon atoms. Particularly preferred meanings oflower alkylene are propylene, ethylene and methylene.

The arylene unit in alkylenearylene or arylenealkylene is preferablyphenylene, unsubstituted or substituted by lower alkyl or lower alkoxy,and the alkylene unit therein is preferably lower alkylene, such asmethylene or ethylene, in particular methylene. These radicals aretherefore preferably phenylenemethylene or methylenephenylene.

Lower alkoxy has, in particular, up to 8 carbon atoms, preferably up to4 carbon atoms, and is, for example, methoxy, ethoxy, propoxy, butoxy,tert-butoxy or hexyloxy.

Arylenealkylenearylene is preferably phenylene(lower alkylene)phenylenehaving up to 8, in particular up to 4, carbon atoms in the alkyleneunit, for example phenyleneethylenephenylene orphenylenemethylenephenylene.

The macromers of the formula (I) can be prepared by processes known perse, for example as follows:

In a first step, a perfluoropolyalkyl ether derivative of formula (IV):

    X.sub.3 --(E).sub.k --Z--CF.sub.2 --(OCF.sub.2).sub.x --(OCF.sub.2 CF.sub.2).sub.y --OCF.sub.2 --Z--(E).sub.k --X.sub.3      (IV)

in which X₃ is --OH, --NH₂, --COOH, --COCl, --NCO or --COOR₅, where--COOR₅ is generally an activated ester in which R₅ is alkyl or arylwhich is unsubstituted or substituted by halogen or cyano, and thevariables Z, E, k, x and y are as defined above, is preferably reactedwith two equivalents of a bifunctional radical of formula (V):

    X.sub.4 --R--X.sub.4                                       (V)

in which R is as defined above and X₄ is a functional radical which iscoreactive with an X₃ and is preferably --OH--, --NH₂, COOH, --COCl,--COOR₅ or --NCO; in the presence or absence of a suitable catalyst,where the reaction of X₃ with X₄ gives a group X₂ ; after which areactive derivative of formula (VI):

    X.sub.4 --R--X.sub.2 --(E).sub.k --Z--CF.sub.2 --(OCF.sub.2).sub.x --(OCF.sub.2 CF.sub.2).sub.y --OCF.sub.2 --Z--(E).sub.k --X.sub.2 --R--X.sub.4                                              (VI)

is obtained which is then preferably reacted with two equivalents of anα,ω-substituted siloxane of formula (VII): ##STR3## where the variablesR₁, R₂, R₃, R₄, n, X₃ and Alk are as defined above, in the presence orabsence of a suitable catalyst, giving a compound of formula (VIII):

    X.sub.3 --Sil--X.sub.2 --R--X.sub.2 --PFPE--X.sub.2 --R--X.sub.2 --Sil--X.sub.3                                            (VIII)

in which PFPE is (E)_(k) --Z--CF₂ --(OCF₂)_(x) --(OCF₂ CF₂)_(y) --OCF₂--Z--(E)_(k), Sil is the siloxane radical ##STR4## and the othervariables are as defined above; after which the reactive intermediate ofthe formula (VIII) is preferably reacted with two equivalents of acompound of the formula (IXa) or (IXb):

    P.sub.1 --(Y).sub.m --L--X.sub.4                           (IXa)

    P.sub.1 --Y.sub.2                                          (IXb)

in the presence or absence of a catalyst, to give the macromer of theformula (I):

    P.sub.1 --(Y).sub.m --(L--X.sub.1).sub.p --Q--(X.sub.1 --L).sub.p --(Y).sub.m --P.sub.1                                     (I)

in which Y₂ is a functional radical which is coreactive with X₃ and ispreferably --OH, --NH₂, --COOH, --COCl, --COOR₅, --CONCO or --NCO, andthe variables are as defined above, and in which X₁ is formed from thereaction of X₃ with X₄ and Y is formed from the reaction of Y₂ with X₃.

The starting materials of formula (IV) for the preparation of theperfluoroalkyl ethers are known and many are commercially available. Forexample, U.S. Pat. No. 3,810,875 and European Patent No. 0211237 (U.S.Pat. No. 4,746,575) describe such compounds. Ausimont, Italy, marketsperfluoroalkyl ether dimethanols under the name Fomblin, for exampleFomblin ZDOL and Fomblin ZDOL-FX. Further Fomblin derivatives of theformula (IV) are commercially available, including, for example, FomblinZDISOC, in which the radical --Z--X₃ in the formula (IV) is CONH--C₆ H₃(CH₃)--NCO; Fomblin ZDEAL, in which the radical Z--X₃ in the formula(IV) is --COOR₅ ; and Fomblin ZDIAC, in which the radical --Z--X₃ in theformula (IV) is --COOH.

Bifunctional radicals having a substitution pattern as per formula (V)exist in large numbers and are commercially available. Examples include,without limitation thereto: diisocyanates, such as isophoronediisocyanate and 2,2,4-trimethylhexane 1,6-diisocyanate; diols, such asglycol and cyclohexane-1,2-diol; dicarboxylic acids, such as adipic acidand maleic acid; diamines, such as ethylenediamine andhexamethylenediamine, diesters, such as diethyl phthalate and dibutylmalonate; derivatives containing various functional groups, such as2aminoethanol, monomethyl malonate, glycolic acid, salicylic acid,glycine and glycine methyl ester.

Preference is given to bifunctional derivatives of the formula (V) whichhave different reactivities irrespective of the nature of theirfunctional radicals X₄. In the case of identical radicals X₄, this isachieved, for example, through different steric requirements in thedirect vicinity of a radical X₄. Examples thereof are isophoronediisocyanate, 2,2,4-trimethylhexane 1,6-diisocyanate and toluene2,4-diisocyanate. The advantage of using bifunctional derivatives offormula (V) of different reactivity is that the chain length of polymerQ (number of segments (a), (b) and (c)) is easily adjustable andcontrollable.

α,ω-substituted siloxanes of formula (VII) are likewise commerciallyavailable, for example α,ω-hydroxypropyl-terminated polydimethylsiloxaneKF6001 from Shin-Etsu.

The novel compounds can be prepared in the presence or absence of asolvent. It is advantageous to use a substantially inert solvent, i.e.,one which does not participate in the reaction. Suitable examplesthereof are ethers, such as tetrahydrofuran (THF), diethyl ether,diethylene glycol dimethyl ether or dioxane, halogenated hydrocarbons,such as chloroform or methylene chloride, bipolar aprotic solvents, suchas acetonitrile, acetone, dimethylformamide (DMF) or dimethyl sulfoxide(DMSO), hydrocarbons, such as hexane, petroleum ether, toluene orxylene, and furthermore pyridine or N-methylmorpholine.

In the preparation of novel compounds, the reactants are advantageouslyemployed in stoichiometric amounts. The reaction temperature can be, forexample, from -30° C. to 150° C., preferably from 0° to roomtemperature. The reaction times are in the range of about 15 minutes to7 days, preferably about 12 hours. If necessary, the reaction is carriedout under argon or nitrogen as protective gas. In urethane-formingreactions, a suitable catalyst, for example, dibutyltin dilaurate(DBTDL), is advantageously added.

The present Material "B" furthermore relates to a polymer comprising aproduct of the polymerization of at least one compound of formula (I) asdefined above and, if desired, at least one vinylic comonomer (a). In apreferred composition of a novel copolymer, the proportion by weight ofa compound of formula (I) is in the range of 100 to 0.5%, in particularin the range of 80 to 10%, preferably in the range of 70 to 30%, basedon the total polymer.

In a preferred polymer comprising a product of the polymerization of atleast one compound of the formula (I), comonomer (a) is absent and thepolymer is a homopolymer.

A comonomer (a) present in the novel polymer can be hydrophilic orhydrophobic or a mixture thereof. Suitable comonomers are, inparticular, those which are usually used in the production of contactlenses and biomedical materials. A hydrophobic comonomer (a) is taken tomean a monomer which typically gives a homopolymer which is insoluble inwater and can absorb less than 10% by weight of water. Analogously, ahydrophilic comonomer (a) is taken to mean a monomer which typicallygives a homopolymer which is soluble in water or can absorb at least 10%by weight of water. Suitable hydrophobic comonomers (a) are, withoutlimitation thereto, C₁ -C₁₈ alkyl and C₃ -C₁₈ cycloalkyl acrylates andmethacrylates, C₃ -C₁₈ alkylacrylamides and -methacrylamides,acrylonitrile, methacrylonitrile, vinyl C₁ -C₁₈ alkanoates, C₂ -C₁₈alkenes, C₂ -C₁₈ haloalkenes, styrene, (lower alkyl)styrene, lower alkylvinyl ethers, C₂ -C₁₀ perfluoroalkyl acrylates and methacrylates andcorrespondingly partially fluorinated acrylates and methacrylates, C₃-C₂ perfluoroalkylethylthiocarbonylaminoethyl acrylates andmethacrylates, acryloxy- and methacryloxyalkylsiloxanes,N-vinylcarbazole, C₁ -C₁₂ alkyl esters of maleic acid, fumaric acid,itaconic acid, mesaconic acid and the like.

Preference is given, for example, to acrylonitrile, C₁ -C₄ alkyl estersof vinylically unsaturated carboxylic acids having 3 to 5 carbon atomsor vinyl esters of carboxylic acids having up to 5 carbon atoms.

Examples of suitable hydrophobic comonomers (a) are methyl acrylate,ethyl acrylate, propyl acrylate, isopropyl acrylate, cyclohexylacrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethylmethacrylate, propyl methacrylate, butyl acrylate, vinyl acetate, vinylpropionate, vinyl butyrate, vinyl valerate, styrene, chloroprene, vinylchloride, vinylidene chloride, acrylonitrile, 1-butene, butadiene,methacrylonitrile, vinyltoluene, vinyl ethyl ether,perfluorohexylethylthiocarbonylaminoethyl methacrylate, isobornylmethacrylate, trifluoroethyl methacrylate, hexafluoroisopropylmethacrylate, hexafluorobutyl methacrylate,tristrimethylsilyloxysilylpropyl methacrylate (TRIS), 3-methacryloxypropylpentamethyldisiloxane andbis(methacryloxypropyl)tetramethyldisiloxane.

Preferred examples of hydrophobic comonomers (a) are methylmethacrylate, TRIS and acrylonitrile.

Suitable hydrophilic comonomers (a) are, without this being anexhaustive list, hydroxyl-substituted lower alkyl acrylates andmethacrylates, acrylamide, methacrylamide, (lower allyl)acrylamides and-methacrylamides, ethoxylated acrylates and methacrylates,hydroxyl-substituted (lower alkyl)acrylamides and -methacrylamides,hydroxyl-substituted lower alkyl vinyl ethers, sodium vinylsulfonate,sodium styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid,N-vinylpyrrole, N-vinyl-2-pyrrolidone, 2-vinyloxazoline,2-vinyl4,4'-dialkyloxazolin-5-one, 2- and 4-vinylpyridine, vinylicallyunsaturated carboxylic acids having a total of 3 to 5 carbon atoms,amino(lower alkyl)- (where the term "amino" also includes quaternaryammonium), mono(lower alkylamino)(lower alkyl) and di(loweralkylamino)(lower alkyl)acrylates and methacrylates, allyl alcohol andthe like. Preference is given, for example, to N-vinyl-2-pyrrolidone,acrylamide, methacrylamide, hydroxyl-substituted lower alkyl acrylatesand methacrylates, hydroxy-substituted (lower alkyl)acrylamides and-methacrylamides and vinylically unsaturated carboxylic acids having atotal of 3 to 5 carbon atoms.

Examples of suitable hydrophilic comonomers (a) are hydroxyethylmethacrylate (HEMA), hydroxyethyl acrylate, hydroxypropyl acrylate,trimethylammonium 2-hydroxy propylmethacrylate hydrochloride (Blemer®QA, for example from Nippon Oil), dimethylaminoethyl methacrylate(DMAEMA), dimethylaminoethylmethacrylamide, acrylamide, methacrylamide,N,N-dimethylacrylamide (DMA), allyl alcohol, vinylpyridine, glycerolmethacrylate, N-(1,1dimethyl-3-oxobutyl)acrylamide,N-vinyl-2-pyrrolidone (NVP), acrylic acid, methacrylic acid and thelike.

Preferred hydrophilic comonomers (a) are trimethylammonium 2-hydroxypropylmethacrylate hydrochloride, 2-hydroxyethyl methacrylate,dimethylaminoethyl methacrylate, trimethylammonium2-hydroxypropylmethacrylate hydrochloride, N,N-dimethylacrylamide andN-vinyl-2-pyrrolidone.

The novel polymers are synthesized in a manner known per se from thecorresponding monomers (the term monomer here also including a macromeraccording to the definition of the formula (I)) by a polymerizationreaction customary to the person skilled in the art. Usually, a mixtureof the abovementioned monomers is warmed with addition of a free-radicalformer. Examples of such free-radical formers are azoisobutyronitrile(AIBN), potassium peroxodisulfate, dibenzoyl peroxide, hydrogen peroxideand sodium percarbonate. If, for example, said compounds are warmed,free radicals form with homolysis, and can then initiate, for example, apolymerization.

A polymerization reaction can particularly preferably be carried outusing a photoinitiator. In this case, the term photopolymerization isused. In the photopolymerization, it is appropriate to add aphotoinitiator which can initiate free-radical polymerization and/orcrosslinking by using light. Examples thereof are customary to theperson skilled in the art; suitable photoinitiators are, in particular,benzoin methyl ether, 1-hydroxycyclohexylphenyl ketone, Darocur andIrgacur products, preferably Darocur® 1173 and Irgacur® 2959. Alsosuitable are reactive photoinitiators, which can be incorporated, forexample, into a macromer, or can be used as a specific comonomer (a).Examples thereof are given in European Patent No. 0632329. Thephotopolymerization can then be initiated by actinic radiation, forexample light, in particular UV light having a suitable wavelength. Thespectral requirements can, if necessary, be controlled appropriately byaddition of suitable photosensitizers.

A polymerization can be carried out in the presence or absence of asolvent. Suitable solvents are in principle all solvents which dissolvethe monomers used, for example water, alcohols, such as lower alkanols,for example ethanol or methanol, furthermore carboxamides, such asdimethylformamide, dipolar aprotic solvents, such as dimethyl sulfoxideor methyl ethyl ketone, ketones, for example acetone or cyclohexanone,hydrocarbons, for example toluene, ethers, for example THF,dimethoxyethane or dioxane, halogenated hydrocarbons, for exampletrichloroethane, and also mixtures of suitable solvents, for examplemixtures of water and an alcohol, for example a water/ethanol orwater/methanol mixture.

A polymer network can, if desired, be reinforced by addition of acrosslinking agent, for example a polyunsaturated comonomer (b). In thiscase, the term crosslinked polymers is used. The invention, therefore,furthermore relates to a crosslinked polymer comprising the product ofthe polymerization of a macromer of the formula (I), if desired with atleast one vinylic comonomer (a) and with at least one comonomer (b).

Examples of typical comonomers (b) are allyl(meth)acrylate, loweralkylene glycol di(meth)acrylate, poly(lower alkylene)glycoldi(meth)acrylate, lower alkylene di(meth)acrylate, divinyl ether,divinyl sulfone, di- and trivinylbenzene, trimethylolpropanetri(meth)acrylate, pentaerythritol tetra(meth)acrylate, bisphenol Adi(meth)acrylate, methylenebis(meth)acrylamide, triallyl phthalate anddiallyl phthalate.

The amount of comonomer (b) used is expressed in a proportion by weightbased on the total polymer and is in the range from 20 to 0.05%, inparticular in the range from 10 to 0.1%, preferably in the range from 2to 0.1%.

3. Material "C"

Material "C" polymers are formed by polymerizing polymerizable macromerswhich contain free hydroxyl groups. Macromers which are built up, forexample, from an aminoalkylated polysiloxane which is derivatized withat least one polyol component containing an unsaturated polymerizableside chain are disclosed. Polymers can be prepared on the one hand fromthe macromers according to the invention by homopolymerization. Themacromers mentioned furthermore can be mixed and polymerized with one ormore hydrophilic and/or hydrophobic comonomers. A special property ofthe macromers according to the invention is that they function as theelement which controls microphase separation between selectedhydrophilic and hydrophobic components in a crosslinked end product. Thehydrophilic/hydrophobic microphase separation is in the region of lessthan 300 nm. The macromers are preferably crosslinked at the phaseboundaries between, for example, an acrylate comonomer on the one handand an unsaturated polymerizable side chain of polyols bonded topolysiloxane on the other hand, by covalent bonds and additionally byreversible physical interactions, for example hydrogen bridges. Theseare formed, for example, by numerous amide or urethane groups. Thecontinuous siloxane phase which exists in the phase composite has theeffect of producing a surprisingly high permeability to oxygen.

The present embodiment of the invention relates to a macromer comprisingat least one segment of the formula (I): ##STR5## in which (a) is apolysiloxane segment,

(b) is a polyol segment which contains at least 4 C atoms, Z is asegment (c) or a group X₁,

(c) is defined as X₂ --R--X₂, wherein

R is a bivalent radical of an organic compound having up to 20 C atomsand each X₂ independently of the other is a bivalent radical whichcontains at least one carbonyl group,

X₁ is defined as X₂, and

(d) is a radical of the formula (II):

    X.sub.3 --L--(Y).sub.k --P.sub.1                           (II)

in which

P₁ is a group which can be polymerized by free radicals;

Y and X₃ independently of one another are a bivalent radical whichcontains at least one carbonyl group;

k is 0 or 1; and

L is a bond or a divalent radical having up to 20 C b atoms of anorganic compound.

A polysiloxane segment (a) is derived from a compound of the formula(III): ##STR6## in which n is an integer from 5 to 500;

99.8-25% of the radicals R₁, R₂, R₃, R₄, R₅ and R₆ independently of oneanother are alkyl and 0.2-75% of the radicals R₁, R₂, R₃, R₄, R₅ and R₆independently of one another are partly fluorinated alkyl, aminoalkyl,alkenyl, aryl, cyanoalkyl, alk-NH-alk-NH₂ or alk-(OCH₂)_(m)--(OCH₂)p--OR₇,

R₇ is hydrogen or lower alkyl, alk is alkylene, and

m and p independently of one another are an integer from 0 to 10, onemolecule containing at least one primary amino or hydroxyl group.

The alkylenoxy groups --(OCH₂ CH₂)_(m) and --(OCH₂)_(p) in the siloxaneof the formula (III) are either distributed randomly in a ligandalk-(OCH₂ CH₂)_(m) --(OCH₂)_(p) --OR₇ or are distributed as blocks in achain.

A polysiloxane segment (a) is linked a total of 1-50 times, preferably2-30 times, and in particular 4-10 times, via a group Z with a segment(b) or another segment (a), Z in an a --Z-- a sequence always being asegment (c). The linkage site in a segment (a) with a group Z is anamino or hydroxyl group reduced by one hydrogen.

In a preferred embodiment, a polysiloxane segment is derived from acompound of the formula (III) in which the radicals R₁, R₂, R₃, R₄, R₅and R₆ are a total of 1-50 times, more preferably 2-30 times, and inparticular 4-10 times, independently either terminally or pendentlyaminoalkyl or hydroxyalkyl, the other variables being as defined above.

In a preferred embodiment, a polysiloxane segment is derived from acompound of the formula (III) in which 95-29% of the radicals R₁, R₂,R₃, R₄, R₅ and R₆ independently of one another are alkyl and 5-71% ofthe radicals R₁, R₂, R₃, R₄, R₅ and R₆ independently of one another arepartly fluorinated alkyl, aminoalkyl, alkenyl, aryl, cyanoalkyl,alk-NH-alk-NH₂ or alk-(OCH₂ CH₂)_(m) --(OCH₂)_(p) --OR₇, and in whichthe variables are as defined above.

In a preferred meaning, n is an integer from 5 to 400, more preferably10 to 250 and particularly preferably 12 to 125.

In a preferred meaning, the two terminal radicals R₁ and R₆ areaminoalkyl or hydroxyalkyl, the other variables being as defined above.

In another preferred meaning, the radicals R₄ and R₅ are 1-50 times,more preferably 2-30 times and in particular 4≧10 times pendentlyaminoalkyl or hydroxyalkyl and the other variables are as defined above.

In another preferred meaning, the radicals R₁, R₂, R₃, R₄, R₅ and R₆ area total of 1-50 times, more preferably 2-30 times and in particular 4-10times, independently both terminally and pendently aminoalkyl orhydroxyalkyl and the other variables are as defined above.

If Z is X₁, X₁ is a bivalent group which contains at least one carbonylgroup. A carbonyl group mentioned is flanked in any manner, ifappropriate, by --O--, --CONH--, --NHCO-- or --NH--.

Examples of bivalent groups Z are typically carbonyls, esters, amides,urethanes, ureas or carbonates.

X₁ is preferably an ester, amide, urethane or urea group, in particularan ester or amide group.

X₂ is defined in the same way as X₁ and is preferably an ester, amide,urethane, carbonate or urea group, more preferably an ester, amide,urethane or urea group and in particular an amide, urethane or ureagroup.

If Z in formula (I) is X₁, a polyol segment b is preferably understoodas meaning a polyol derived from a carbohydrate, carbohydratemonolactone or carbohydrate dilactone. A carbohydrate is understood asmeaning a mono-, di-, tri-, tetra-, oligo- or polysaccharide. Acarbohydrate lactone is understood as meaning the lactone of an aldonicor uronic acid. An aldonic or uronic acid is, for example, a carboxylicacid formed by oxidation of a mono-, di-, tri-, tetra-, oligo- orpolysaccharide. Examples of aldonic acid lactones are gluconolactone,galactonolactone, lactobionolactone or maltoheptaonolactone; examples ofuronic acid lactones are glucuronic acid lactone, mannuronic acidlactone or iduronic acid lactone. An example of a carbohydrate dilactoneis D-glucaro-1,4:6,3-dilactone.

A carbohydrate lactone reacts, for example, with a primary amino groupor a hydroxyl group of segment (a) to form a covalent amide or esterbond of the type X₁. Such linkages are the constituent of a furtherpreferred embodiment of macromers according to the invention. Suchmacromers have an alternating distribution of segments of type (a) and(b) which are interrupted by X₁.

This embodiment of the invention preferably relates to a macromer of theformula (IV): ##STR7## in which the variables are as defined above.

An embodiment of the invention furthermore preferably relates to amacromer according to formula (V): ##STR8## in which the polysiloxanesegment (a) contains q pendent ligands x is 0, 1 or 2,

q has an average numerical value of 1-20, preferably 1-10, and inparticular 1-5, and

the segments (b) in a macromer according to the formula (V) are linkedin total (per molecule) with up to 20, preferably with up to 15, and inparticular with up to 6 polymerizable segments (d).

An embodiment of the invention furthermore preferably relates to amacromer according to formula (VI): ##STR9## in which a linear sequenceis present, x is 0, 1 or 2,

q has an average numerical value of 1-20, preferably 1 -10, and inparticular 1-5, and

the segments (b) in a macromer according to the formula (VI) are linkedin total (per molecule) with up to 20, preferably with up to 15, and inparticular with up to 6 polymerizable segments (d).

An embodiment of the invention furthermore very preferably relates to amacromer according to formula (VII): ##STR10## in which x is 0, 1 or 2,and the average number of segments (d) per molecule of the formula (VII)is preferably in the range from 2 to 5, and very preferably is in therange from 3 to 4.

A polyol segment (b) is derived from a polyol which carries no lactonegroup if the group Z is a segment (c). Examples of such polyols are a1,2-polyol, for example the reduced monosaccharides, for examplemannitol, glucitol, sorbitol or iditol, a 1,3-polyol, for examplepolyvinyl alcohol (PVA), which is derived from partly or completelyhydrolysed polyvinyl acetate, and furthermore amino-terminal PVAtelomers, aminopolyols, aminocyclodextrins, aminomono-, -di-, -tri-,-oligo- or -polysaccharides or cyclodextrin derivatives, for examplehydroxypropylcyclodextrin. An abovementioned carbohydrate dilactone canbe reacted, for example, with preferably 2 equivalents of anamino-terminal PVA telomer to give a polyol macromer which carries, inthe central part, the carbohydrate compound derived from the dilactone.Such polyols of this composition are likewise understood to be asuitable polyol.

As illustrated in formula (I), a segment (b) carries at least onevinylic polymerizable segment (d), a linkage of a segment (d) via thebivalent radical X₃ thereof to an amino or hydroxyl group, of a segment(b), reduced by a hydrogen atom being intended.

A vinylic polymerizable segment (d) is incorporated either terminally orpendently preferably 1-20 times, more preferably 2-15 times, and inparticular 2-6 times, per macromer molecule according to the invention.

A vinylic polymerizable segment (d) is incorporated terminally and alsopendently as desired (as a terminal/pendent mixture) preferably 1-20times, more preferably 2-15 times and in particular 2-6 times, permacromer molecule according to the invention.

A group P₁ which can be polymerized by free radicals is, for example,alkenyl, alkenylaryl or alkenylarylenealkyl having up to 20 C atoms.Examples of alkenyl are vinyl, allyl, 1-propen-2-yl, 1-buten-2- or -3-or 4-yl, 2-buten-3-yl and the isomers of pentenyl, hexenyl, octenyl,decenyl or undecenyl. Examples of alkenylaryl are vinylphenyl,vinylnaphthyl or allylphenyl. An example of alkenylarylenealkyl isvinylbenzyl.

P₁ is preferably alkenyl or alkenylaryl having up to 12 C atoms, morepreferably alkenyl having up to 8 C atoms and in particular alkenylhaving up to 4 C atoms.

L is preferably alkylene, arylene, a saturated bivalent cycloaliphaticgroup having 6 to 20 carbon atoms, arylenealkylene, alkylenearylene,alkylenearylenealkylene or arylenealkylenearylene. In a preferredmeaning, L furthermore is preferably a bond.

In a preferred meaning, L is a divalent radical having up to 12 C atoms,and more preferably a divalent radical having up to 8 C atoms. In apreferred meaning, L furthermore is alkylene or arylene having up to 12C atoms. A very preferred meaning of L is lower alkylene, in particularlower alkylene having up to 4 C atoms.

Y is preferably a carbonyl, ester, amide or urethane group, inparticular a carbonyl, ester or amide group, and very preferably acarbonyl group.

In another preferred meaning, Y is absent, i.e., k is 0.

In a preferred meaning, X₃ is a urethane, urea, ester, amide orcarbonate group, more preferably a urethane, urea, ester or amide group,and in particular a urethane or urea group. A vinylic polymerizablesegment (d) is derived, for example, from acrylic acid, methacrylicacid, methacryloyl chloride, 2-isocyanatoethyl methacrylate (IEM), allylisocyanate, vinyl isocyanate, the isomeric vinylbenzyl isocyanates oradducts of hydroxyethyl methacrylate (HEMA) and 2,4-tolylenediisocyanate (TDI) or isophorone diisocyanate (IPDI), in particular the1:1 adduct. The invention furthermore preferably relates to a macromerin which a segment (d) is incorporated either terminally or pendently oras a terminal/pendent mixture 5 times. The invention furthermorepreferably relates to a macromer in which a segment (d) is incorporatedterminally 5 times.

The diradical R is, for example, alkylene, arylene, alkylenearylene,arylenealkylene or arylenealkylenearylene having up to 20 carbon atoms,a saturated bivalent cycloaliphatic group having 6 to 20 carbon atoms orcycloalkylenealkylenecycloalkylene having 7 to 20 carbon atoms.

In a preferred meaning, R is alkylene, arylene, alkylenearylene,arylenealkylene or arylenealkylenearylene having up to 14 carbon atomsor a saturated bivalent cycloaliphatic group having 6 to 14 carbonatoms.

In a preferred meaning, R is alkylene, arylene, alkylenearylene orarylenealkylene having up to 14 carbon atoms, or a saturated bivalentcycloaliphatic group having 6 to 14 carbon atoms. In a preferredmeaning, R is alkylene or arylene having up to 12 carbon atoms, or asaturated bivalent cycloaliphatic group having 6 to 14 carbon atoms.

In a preferred meaning, R is alkylene or arylene having up to 10 carbonatoms, or is a saturated bivalent cycloaliphatic group having 6 to 10carbon atoms.

In a very preferred meaning, a segment (c) is derived from adiisocyanate, for example from hexane 1,6-diisocyanate,2,2,4-trimethylhexane 1,6-diisocyanate, tetramethylene diisocyanate,phenylene 1,4-diisocyanate, toluene 2,4-diisocyanate, toluene2,6-diisocyanate, m- or p-tetramethylxylene diisocyanate, isophoronediisocyanate or cyclohexane 1,4-diisocyanate.

A preferred embodiment of segment (c) is furthermore derived from adiisocyanate in which the isocyanate groups have different reactivities.The different reactivity is influenced, in particular, by the spatialrequirements and/or electron density in the neighbourhood of anisocyanate group.

The average molecular weight of a macromer according to the invention ispreferably in the range from about 300 to about 30,000, very preferablyin the range from about 500 to about 20,000, more preferably in therange from about 800 to about 12,000, and particularly preferably in therange from about 1000 to about 10,000.

A preferred embodiment of the macromer has a segment sequence of theformula (VIII):

    b--Z--a--{c--a}.sub.r --(Z-b).sub.t                        (VIII)

in which

r is an integer from 1 to 10, preferably from 1 to 7, and in particularfrom 1 to 3;

t is 0 or 1, and preferably 1;

a linear (c-a) chain which may or may not be terminated by a segment (b)is present (t=1 ); and

the above preferences apply to the total number of segments (d), whichare preferably bonded to a segment (b).

A preferred embodiment of the macromer has a segment sequence of formula(IX):

    b--Z--a--{c--a--(Z--b).sub.t }.sub.r                       (IX)

in which

the sequence (c--a)--(Z--b)t hangs pendently r times on the segment (a)and may or may not be terminated by a segment (b);

r is an integer from 1 to 10, preferably from 1 to 7, and in particularfrom 1 to 3;

t is 0 or 1, and is preferably 1;

Z is a segment (c) or a group X₁ ; and

the above preferences apply to the total number of segments (d), whichare preferably bonded to a segment (b).

Another preferred embodiment of the macromer has a segment sequence offormula (X):

    b--c--{a--c}.sub.s --B                                     (X)

in which

s is an integer from 1 to 10, preferably from 1 to 7, and in particularfrom 1 to 3;

B is a segment (a) or (b); and

the above preferences apply to the number of segments (d), which arebonded to a segment (b).

Another preferred embodiment of the macromer has a segment sequence ofthe formula (XI):

    B--(c--b).sub.s --Z--a--(b).sub.t                          (XI)

in which

the structures are linear,

s is an integer from 1 to 10, preferably from 1 to 7, and in particularfrom 1 to 3;

B is a segment (a) or (b);

t is 0 or 1,and

the above preferences apply to the number of segments (d), which arebonded to a segment (b).

The ratio of the number of segments (a) and (b) in a macromer accordingto the Material "C" embodiment of the invention is preferably in a rangeof (a):(b)=3:4, 2:3, 1:2, 1:1, 1:3 or 1:4. The total sum of segments (a)and (b) or, where appropriate, (a) and (b) and (c) is in a range from 2to 50, preferably 3 to 30, and in particular in the range from 3 to 12.

Alkyl has up to 20 carbon atoms and can be straight-chain or branched.Suitable examples include dodecyl, octyl, hexyl, pentyl, butyl, propyl,ethyl, methyl, 2-propyl, 2-butyl or 3-pentyl.

Arylene is preferably phenylene or naphthylene, which is unsubstitutedor substituted by lower alkyl or lower alkoxy, in particular1,3-phenylene, 1,4-phenylene or methyl-1,4-phenylene; or 1,5-naphthyleneor 1,8-naphthylene.

Aryl is a carbocyclic aromatic radical, which is unsubstituted orsubstituted by preferably lower alkyl or lower alkoxy. Examples arephenyl, toluyl, xylyl, methoxyphenyl, t-butoxyphenyl, naphthyl orphenanthryl.

A saturated bivalent cycloaliphatic group is preferably cycloalkylene,for example cyclohexylene or cyclohexylene-lower alkylene, for examplecyclohexylenemethylene, which is unsubstituted or substituted by one ormore lower alkyl groups, for example methyl groups, for exampletrimethylcyclohexylenemethylene, for example the bivalent isophoroneradical. The term "lower" in the context of this invention in connectionwith radicals and compounds, unless defined otherwise, means, inparticular, radicals or compounds having up to 8 carbon atoms,preferably having up to 4 carbon atoms.

Lower alkyl has, in particular, up to 8 carbon atoms, preferably up to 4carbon atoms, and is, for example, methyl, ethyl, propyl, butyl,tert-butyl, pentyl, hexyl or isohexyl.

Alkylene has up to 12 carbon atoms and can be straight-chain orbranched. Suitable examples include decylene, octylene, hexylene,pentylene, butylene, propylene, ethylene, methylene, 2-propylene,2-butylene or 3-pentylene.

Lower alkylene is alkylene having up to 8, and particularly preferablyhaving up to 4 carbon atoms. Particularly preferred examples of loweralkylenes are propylene, ethylene and methylene.

The arylene unit of alkylenearylene or arylenealkylene is preferablyphenylene, which is unsubstituted or substituted by lower alkyl or loweralkoxy, and the alkylene unit of this is preferably lower alkylene, suchas methylene or ethylene, in particular methylene. Such radicals aretherefore preferably phenylenemethylene or methylenephenylene.

Lower alkoxy has, in particular, up to 8 carbon atoms, preferably up to4 carbon atoms, and is, for example, methoxy, ethoxy, propoxy, butoxy,tert-butoxy or hexyloxy.

Partly fluorinated alkyl is understood as meaning alkyl in which up to90%, preferably up to 70%, and in particular up to 50%, of the hydrogensare replaced by fluorine.

Arylenealkylenearylene is preferably phenylene-lower alkylene-phenylenehaving up to 8, and in particular having up to 4 carbon atoms in thealkylene unit, for example phenylenethylenephenylene orphenylenemethylenephenylene.

A monosaccharide in the context of the present invention is understoodas meaning an aldopentose, aldohexose, aldotetrose, ketopentose orketohexose.

Examples of an aldopentose are D-ribose, D-arabinose, D-xylose orD-lyose; examples of an aldohexose are D-allose, D-altrose, D-glucose,D-mannose, D-gulose, D-idose, D-galactose, D-talose, L-fucose orL-rhamnose; examples of a ketopentose are D-ribulose or D-xylulose;examples of a tetrose are D-erythrose or threose; and examples of aketohexose are D-psicose, D-fructose, D-sorbose or D-tagatose. Examplesof a disaccharide are trehalose, maltose, somaltose, cellobiose,gentiobiose, saccharose, lactose, chitobiose, N,N-diacetylchitobiose,palatinose or sucrose. Raffinose, panose or maltotriose may be mentionedas an example of a trisaccharide. Examples of an oligosaccharide aremaltotetraose, maltohexaose, chitoheptaose and furthermore cyclicoligosaccharides, such as cyclodextrins.

Cyclodextrins contain 6 to 8 identical units of α-1,4-glucose. Someexamples are α-, β- and γ-cyclodextrin, derivatives of suchcyclodextrins, for example hydroxypropylcyclodextrins, and branchedcyclodextrins.

The macromers according to this embodiment of invention can be preparedby processes known per se, for example as follows.

In a first step, a polysiloxane containing at least one primary amino-or hydroxyalkyl group is reacted with a carbohydrate lactone, an amideor ester bond being formed and a compound of the formula (XIIa) or(XIIb) being formed:

    (a--Z--b).sub.q                                            (XIIa)

    a--(Z--b).sub.q                                            (XIIb)

in which the variables are as defined above and Z is a group X₁,

after which the compound (XII) is reacted with an unsaturatedpolymerizable compound of the formula XII):

    X.sub.4 --L--(Y).sub.k --P.sub.1                           (XIII)

in which X₄ is a group which is coreactive with a hydroxyl or aminogroup of segment (b), an X₃ group of a segment (d) according to formula(II) being formed from such a reaction, where X₄ is preferably --COOH,--COOR₁₀, --COCl or --NCO, in which R₁₀ is alkyl, or is aryl which isunsubstituted or substituted by lower alkyl or lower alkoxy, and theother variables are as defined above,

after which a macromer according to the formula (IV) or (V) is formed##STR11## in which the segments (d) are incorporated terminally orpendently.

Another process starts from a polysiloxane (a) which contains terminalprimary amino- or hydroxyalkyl groups and is reacted with a carbohydratedilactone to form linear structures of the formula (XIV):

    .paren open-st.a--X.sub.1 --b.paren close-st..sub.q        (XIV)

in which the variables are as defined and preferred above, after which acompound of the formula (XIV) is reacted with a compound of the formula(XIII) analogously to the above process to give a macromer of theformula (VI): ##STR12## in which the variables are as defined andpreferred above.

Another process starts from a polysiloxane (a) which contains terminalprimary amino- or hydroxyalkyl groups and is initially reacted with abifunctional compound of the formula (XV):

    X.sub.4 --R--X.sub.4                                       (XV)

in which X₄ is a group which is coreactive with a hydroxyl or aminogroup of segment (a), an X₂ group of a segment (c) being formed fromsuch a reaction, where X₄ is preferably --COOH, --COOR₁₀, --COCl or--NCO, in which R₁₀ is alkyl, or aryl which is unsubstituted orsubstituted by lower alkyl or lower alkoxy, and R is as defined above,

after which this intermediate is reacted with a polyol which carries nolactone group to give a compound of the formula (XVI):

    b--c--{a--c}.sub.s --b                                     (XVI)

in which the variables are as defined and preferred above, after whichthe compound of the formula (XVI) is reacted with a compound of theformula (XIII) to give a macromer of the formula (X):

    b--c--{a--c}.sub.s --B                                     (X)

in which s is an integer from 1 to 10, preferably from 1 to 7, and inparticular from 1 to 3; B is a segment (a) or (b); and the abovepreferences apply to the number of segments (d) which are bonded to asegment (b).

Another process starts from a bifunctional compound of the formula (XV):

    X.sub.4 --R--X.sub.4                                       (XV)

which is reacted with an excess of polysiloxane (a) to give an--a--(c--a)_(r) -- sequence, in which the above meanings apply, afterwhich, in a second step, the intermediate is reacted with a polyol whichcarries no lactone to give a compound of the formula (XVII):

    b--Z--a--{c--a}.sub.r --Z--b                               (XVII)

after which the compound (XVII) is reacted with the compound (XIII) togive a macromer of the formula (VIII):

    b--Z--a--{c--a}.sub.r --(Z--b).sub.t                       (VIII)

in which r is an integer from 1 to 10, preferably from 1 to 7, and inparticular from 1 to 3; t is 0 or 1, and is preferably 1; in which alinear (c--a) chain, which may or may not be terminated by a segment(b), is present (t=1); and the above preferences apply to the totalnumber of segments (d), which are preferably bonded to a segment (b).

Another process starts from a carbohydrate lactone which is reacted in afirst step with a compound of the formula (XIII), the lactone functionbeing retained, after which the intermediate is reacted with apolysiloxane containing at least one amino or hydroxyl group to give acompound of the formula (IV) or (V): ##STR13## in which q is typically 1or 2, and in which the above meanings and preferences otherwise apply,and the segments (d) are incorporated terminally or pendently.

The present embodiment of the invention furthermore relates to theintermediates which are novel and which occur during synthesis of themacromers according to the invention.

The invention therefore furthermore relates to a compound of the formula(XIIa):

    (a--Z--b).sub.q                                            (XIIa)

in which q is greater than 1,

(a) is derived from a polysiloxane as defined by formula (I) above and

(b) is derived from a carbohydrate dilactone.

An embodiment of the invention furthermore relates to a compound of theformula (XIIb):

    a--(Z--b).sub.q                                            (XIIb)

in which Z, (b) and q are as defined and preferred above, but with theproviso that a segment (a) is derived from a compound of the formula(III): ##STR14## in which n is an integer from 5 to 500; 99.8-25% of theradicals R₁, R₂, R₃, R₄, R₅ and R₆ independently of one another arealkyl and 0.2-75% of the radicals R₁, R₂, R₃, R₄, R₅ and R₆independently of one another are partly fluorinated alkyl, aminoalkyl,alkenyl, aryl, cyanoalkyl, alk-NH-Alk-NH₂ or alk-(OCH₂ CH₂)_(m)--(OCH₂)_(p) --OR₇ in which R₇ is hydrogen or lower alkyl, alk isalkylene and m and p independently of one another are an integer from 0to 10, one molecule containing at least one primary amino or hydroxylgroup and at least one partly fluorinated alkyl group.

The invention furthermore relates to a compound of the formula (XVI):

    b--c--{a--c}.sub.s --b                                     (XVI)

in which a segment (b) is derived from a polyol which carries no lactoneand the other variables are as defined and preferred above.

An embodiment of the invention furthermore relates to a compound of theformula (XVII):

    b--Z--a--{c--a}.sub.r --Z--b                               (XVII)

in which a segment (b) is derived from a polyol which carries no lactoneand the other variables are as defined and preferred above.

A siloxane (a) containing at least one primary amino or hydroxyl groupis, for example, commercially obtainable. Examples are KF6002, KF-8003,X-22-161C (Shin Etsu) or GP4 (Genesee). Other siloxanes can besynthesized with the aid of published processes.

A polyol (b) required for the synthesis is as a rule commerciallyobtainable. Examples are gluconolactone or lactobionolactone. Otherwise,they can be synthesized with the aid of a published process.

The compounds according to the invention can be prepared in the presenceor absence of a solvent. A solvent which is largely inert, i.e., doesnot participate in the reaction, is advantageously used. Suitableexamples of these are ethers, such as tetrahydrofuran (THF),1,2-dimethoxyethane, diethylene glycol dimethyl ether or dioxane,halogenated hydrocarbons, such as chloroform or methylene chloride,bipolar aprotic solvents, such as acetonitrile, acetone,dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), hydrocarbons, suchas toluene or xylene, and furthermore pyridine or N-methylmorpholine.

The reactants are advantageously employed in stoichiometric amounts forthe preparation of the compounds according to the invention. Thereaction temperature can be, for example, from -30° C. to 150° C. Therange from 0° C. to 40° C. is a preferred temperature range. Thereaction times here are in the range from about 15 minutes to 7 days,preferably in the region of about 12 hours. If necessary, the reactionis carried out under argon or nitrogen as an inert gas. A suitablecatalyst is advantageously added for urethane-forming reactions, forexample dibutyltin dilaurate (DBTDL).

The present invention furthermore relates to a polymer comprising apolymerization product of at least one macromer according to theinvention as defined above and, if appropriate, at least one vinyliccomonomer (a).

The preferred composition of a polymer according to the inventioncomprises a weight content, with respect to the total polymer, of amacromer according to the invention in the range from 100 to 0.5%, inparticular in the range from 80 to 10%, and preferably in the range from70 to 30%.

In a preferred polymer comprising a polymerization product of at leastone macromer according to the invention, comonomer (a) is absent and thepolymer is preferably a homopolymer.

A comonomer (a) which is contained in a polymer according to theinvention can be hydrophilic or hydrophobic or a mixture of both.Suitable comonomers include, in particular, those which are usually usedfor the preparation of contact lenses and biomedical materials. Ahydrophobic comonomer (a) is understood as meaning monomers whichtypically give, as a homopolymer, polymers which are water-insoluble andcan absorb less than 10% by weight of water.

Analogously, a hydrophilic comonomer (a) is understood as meaning amonomer which typically gives, as a homopolymer, a polymer which iswater-soluble or can absorb at least 10% by weight of water.

Suitable hydrophobic comonomers (a) include, without this list beingexhaustive, C₁ -C₁₈ alkyl and C₃ -C₁₈ cycloalkyl acrylates andmethacrylates, C₃ -C₁₈ alkylacrylamides and -methacrylamidesacrylonitrile, methacrylonitrile, vinyl C₁ -C₁₈ alkanoates, C₂ -C₁₈alkenes, C₂ -C₁₈ haloalkenes, styrene, lower alkyl styrene, lower alkylvinyl ethers, C₂ -C₁₀ perfluoroalkyl acrylates and methacrylates orcorrespondingly partly fluorinated acrylates and methacrylates, C₃ -C₁₂perfluoroalkyl-ethyl-thiocarbonylaminoethyl acrylates and methacrylates,acryloxy- and methacryloxy-alkylsiloxanes, N-vinylcarbazole and C₁ -C₂alkyl esters of maleic acid, fumaric acid, itaconic acid, mesaconic acidand the like. Preferred comonomers are, for example, acrylonitrile, C₁-C₄ alkyl esters of vinylically unsaturated carboxylic acids having 3 to5 carbon atoms, or vinyl esters of carboxylic acids having up to 5carbon atoms.

Examples of suitable hydrophobic comonomers (a) include methyl acrylate,ethyl acrylate, propyl acrylate, isopropyl acrylate, isobutyl acrylate(IBA), isooctyl acrylate (OA), isodecyl acrylate (DA), cyclohexylacrylate, 2-ethylhexyl acrylate (EHA), methyl methacrylate, ethylmethacrylate, propyl methacrylate, butyl acrylate, vinyl acetate, vinylpropionate, vinyl butyrate, vinyl valerate, styrene, chloroprene, vinylchloride, vinylidene chloride, acrylonitrile, 1-butene, butadiene,methacrylonitrile, vinyl toluene, vinyl ethyl ether,perfluorohexylethylthiocarbonylaminoethyl methacrylate, isobornylmethacrylate, trifluoroethyl methacrylate, hexafluoroisopropylmethacrylate, hexafluorobutyl (meth)acrylate (HFBMA and HFBA),tris-trimethylsilyloxy-silyl-propyl methacrylate (TRIS),3-methacryloxypropylpentamethyldisiloxane andbis(methacryloxypropyl)tetramethyldisiloxane. Preferred examples ofhydrophobic comonomers (a) are methyl methacrylate, IBA, HFBA, HFBMA,OA, EHA, DA, TRIS and acrylonitrile.

Suitable hydrophilic comonomers (a) include, without this list beingconclusive, hydroxyl-substituted lower alkyl acrylates andmethacrylates, acrylamide, methacrylamide, lower alkylacrylamides and-methacrylamides, ethoxylated acrylates and methacrylates,hydroxylsubstituted lower alkylacrylamides and -methacrylamides,hydroxyl-substituted lower alkyl vinyl ethers, sodium vinylsulfonate,sodium styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid,N-vinylpyrrole, N-vinyl-2-pyrrolidone, 2-vinyloxazoline,2-vinyl-4,4'-dialkyloxazolin-5-one, 2- and 4-vinylpyridine, vinylicallyunsaturated carboxylic acids having a total of 3 to 5 carbon atoms,amino-lower alkyl (where the term "amino" also includes quaternaryammonium), mono-lower alkylamino-lower alkyl and di-loweralkylamino-lower alkyl acrylates and methacrylates, allyl alcohol andthe like. Preferred comonomers are, for example, N-vinyl-2-pyrrolidone,acrylamide, methacrylamide, hydroxyl-substituted lower alkyl acrylatesand methacrylates, hydroxyl-substituted lower alkylacrylamides and-methacrylamides and vinylically unsaturated carboxylic acids having atotal of 3 to 5 carbon atoms.

Examples of suitable hydrophilic comonomers (a) include hydroxyethylmethacrylate (HEMA), hydroxyethyl acrylate, hydroxypropyl acrylate,trimethylammonium-2-hydroxypropyl methacrylate hydrochloride (Blemer®QA,for example from Nippon Oil), dimethylaminoethyl meth acrylate (DMAEMA),dimethylaminoethyl methacrylamide, acrylamide, methacrylamide,N,N-dimethylacrylamide (DMA), allyl alcohol, vinylpyridine, glycerolmethacrylate, N-(1,1-dimethyl-3-oxobutyl)acrylamide,N-vinyl-2-pyrrolidone (NVP), acrylic acid, methacrylic acid and thelike.

Preferred hydrophilic comonomers (a) are 2-hydroxyethyl methacrylate,dimethylaminoethyl methacrylate, trimethylammonium-2-hydroxypropylmethacrylate hydrochloride, N,N-dimethylacrylamide andN-vinyl-2-pyrrolidone.

The polymers according to the invention are built up in a manner knownper se from the corresponding monomers (the term monomers here alsoincluding a macromer according to the invention) by a polymerizationreaction with which the expert is familiar. Usually, a mixture of theabovementioned monomers is heated, with the addition of an agent whichforms free radicals. Such an agent which forms free radicals is, forexample, azoisobutyronitrile (AIBN), potassium peroxodisulfate,dibenzoyl peroxide, hydrogen peroxide or sodium percarbonate. If thecompounds mentioned are heated, for example, free radicals are thenformed, by homolysis, and can then, for example, initiate apolymerization.

A polymerization reaction can particularly preferably be carried outusing a photoinitiator. Photopolymerization is the term used in thiscase. For photopolymerization, a photoinitiator which can initiate freeradical polymerization and/or crosslinking by the use of light issuitably added. Examples of this are familiar to the expert, andspecifically, suitable photoinitiators are benzoin methyl ether,1-hydroxycyclohexyl phenyl ketone and Darocur and Irgacur types,preferably Darocur 1173® and Darocur 2959®. Reactive photoinitiatorswhich can be incorporated, for example, into a macromer or can be usedas a special comonomer (a) are also suitable. Examples of these are tobe found in EP 632 329. The photopolymerization can then be triggeredoff by actinic radiation, for example light, in particular UV light of asuitable wavelength. The spectral requirements can be controlledaccordingly, if appropriate, by addition of suitable photosensitizers.

Polymerization can be carried out in the presence or absence of asolvent. Suitable solvents are in principle all solvents which dissolvethe monomers used, for example water, alcohols, such as lower alkanols,for example ethanol or methanol, and furthermore carboxylic acid amides,such as dimethylformamide, dipolar aprotic solvents, such as dimethylsulfoxide or methyl ethyl ketone, ketones, for example acetone orcyclohexanone, hydrocarbons, for example toluene, ethers, for exampleTHF, dimethoxyethane or dioxane, and halogenated hydrocarbons, forexample trichloroethane, and also mixtures of suitable solvents, forexample mixtures of water with an alcohol, for example a water/ethanolor a water/methanol mixture.

If appropriate, a polymer network can be intensified by addition of aso-called crosslinking agent, for example a polyunsaturated comonomer(b). The invention furthermore relates to a polymer comprising thepolymerization product of a macromer according to the invention with, ifappropriate, at least one vinylic comonomer (a) and with at least onecomonomer (b).

Examples of typical comonomers (b) are, for example,allyl(meth)acrylate, lower alkylene glycol di(meth)acrylate, poly loweralkylene glycol di(meth)acrylate, lower alkylene di(meth)acrylate,divinyl ether, divinyl sulfone, di- or trivinylbenzene,trimethylolpropane tri(methacrylate, pentaerythritoltetra(meth)acrylate, bisphenol A di(meth)acrylate,methylenebis(meth)acrylamide, triallyl phthalate or dialkyl phthalate.

The amount of comonomer (b) used is expressed in the weight content withrespect to the total polymer and is in the range from 20 to 0.05%, inparticular in the range from 10 to 0.1%, and preferably in the rangefrom 2 to 0.1%.

4. "Material D"

Another advantageous embodiment of the present invention relates to theuse of a siloxane-containing macromer which is formed from apoly(dialkylsiloxane)dialkoxyalkanol having the following structure:##STR15## where n is an integer from about 5 to about 500, preferablyabout 20 to 200, more preferably about 20 to 100;

the radicals R₁, R₂, R₃, and R₄, independently of one another, are loweralkylene, preferably C₁ -C₆ alkylene, more preferably C₁ -C₃ alkylene,wherein in a preferred embodiment, the total number of carbon atoms inR₁ and R₂ or in R₃ and R₄ is greater than 4; and

R₅, R₆, R₇, and R₈, independently of one another, are lower alkyl,preferably C₁ -C₆ alkyl, more preferably C₁ -C₃ alkyl.

The general structure of the Material D macromer follows:

ACRYLATE-LINK-ALK-O-ALK-PDAS-ALK-O-ALK-LINK-ACRYLATE

where the ACRYLATE is selected from acrylates and methacrylates; LINK isselected from urethanes and diurethane linkages, ALK-O-ALK is as definedabove (R₁ --O--R₂ or R₃ O--R₄), and PDAS is a poly(dialkylsiloxane).

For example, a Material D macromer may be prepared by reactingisophorone diisocyanate, 2-hydroxyethyl(meth)acrylate and apoly(dialkylsiloxane)dialkoxyalkanol in the presence of a catalyst.

A preferred Material D macromer may be prepared by reacting a slightexcess of isocyanatoalkyl methacrylate, especially isocyanatoethylmethacrylate (IEM), with a poly(dialkylsiloxane)dialkoxyalkanol,preferably poly(dimethylsiloxane)dipropoxyethanol, in the presence of acatalyst, especially an organotin catalyst such as dibutyltin dilaurate(DBTL). The primary resulting structure is as follows: ##STR16## whereR₉ and R₁₁ are alkylene; preferably C₁₋₆ alkylene, more preferablyethylene;

R₁₀ and R₁₂ are methyl or hydrogen.

The "Material D" prepolymer mixture may be formed by mixing theaforementioned siloxane-containing macromer with one or more hydrophilicmonomers and a thermoinitiator or a photoinitiator such as Darocur®1173. A solvent, such as hexanol, is preferably added to homogenize themixture. Preferably, an appropriate amount of TRIS is added to lower themodulus of elasticity to a desired level. The ionoperm monomer ormonomers may be selected from any of the aforementioned ionoperm orhydrophilic monomers. Preferably, the ionoperm monomer is selected fromthe group consisting of acrylates, methacrylates, acrylamides,methacrylamides and mixtures thereof. More preferably, the ionopermmonomers are selected from dimethylacrylamide (DMA) and methacrylic acid(MAA).

A preferred "Material D" prepolymer mixture, in weight percentages basedon total mixture weight, includes about 35 to 60% Material D macromer;about 6 to 25% TRIS; about 15 to 35% ionoperm monomer; about 0.1 to 1%photoinitiator; and about 10 to 20% solvent. A more preferred "MaterialD" prepolymer mixture, in weight percentages based on total mixtureweight, includes the following: about 40 to 55% Material D macromer;about 8 to 16% TRIS; about 20 to 30% dimethylacrylamide; about 0.2 to 2%methacrylic acid; about 0.1 to 1% photoinitiator; and about 10 to 20%solvent. A particularly preferred "Material D" prepolymer mixture, inweight percentages based on total mixture weight, includes thefollowing: about 44 to 50% Material D macromer; about 10 to 12% TRIS;about 22 to 26% dimethylacrylamide; about 0 to 1% methacrylic acid;about 0.2 to 0.6% photoinitiator; and about 10 to 20% solvent.

The prepolymer mixture may be formed into lenses and other ophthalmicdevices by any of a number of techniques known in the art and disclosedherein. Preferably, the prepolymer mixture is conveyed into a concavehalf of a lens mold, the convex mold half is mated with the concave moldhalf, and an appropriate amount of radiation is applied to initiatepolymerization. While ultraviolet (UV) radiation is preferred, a numberof other energy sources known in the art and disclosed herein may alsobe used.

The Material D ophthalmic lens is preferably a polymerization product ofthe following macromeric and monomeric components, based on total weightof polymerizable material:

(a) about 45 to about 65 percent Material D macromer;

(b) about 5 to about 25 percent TRIS; and

(c) about 20 to about 40 percent ionoperm monomer.

The Material D ophthalmic lens is more preferably a polymerizationproduct of the following macromeric and monomeric components, based ontotal weight of polymerizable material:

(a) about 50 to about 60 percent Material D macromer;

(b) about 10 to about 20 percent TRIS; and

(c) about 25 to about 35 percent ionoperm monomer.

In a preferred embodiment, the Material D ophthalmic lens is apolymerization product of the following macromeric and monomericcomponents, based on total weight of polymerizable material:

(a) about 50 to about 60 percent Material D macromer;

(b) about 10 to about 20 percent TRIS;

(c) about 25 to about 35 percent DMA; and

(d) up to about 2 percent MAA.

In another preferred embodiment, about 0.2 to 1.0 weight percent MAA isused, together with the components (a), (b), and (c) in the above-citedamounts.

II. OPHTHALMICALLY COMPATIBLE SURFACES

The ophthalmic lenses of the present invention have a surface which isbiocompatible with ocular tissue and ocular fluids during the desiredextended period of contact. In one preferred embodiment, the ophthalmiclenses of the present invention include a core material, as definedabove, surrounded, at least in part, by a surface which is morehydrophilic and lipophobic than the core material. A hydrophilic surfaceis desirable in order to enhance the compatibility of the lens with theocular tissues and tear fluids. As surface hydrophilicity increases,undesirable attraction and adherence of lipids and proteinaceous mattertypically decreases. There are factors other than surfacehydrophilicity, such as immunological response, which may contribute todeposit accumulation on the lens. Deposition of lipids and proteinaceousmatter causes haze on the lens, thereby reducing visual clarity.Proteinaceous deposits may also cause other problems, such as irritationto the eye. After extended periods of continuous or intermittent wear,the lens must be removed from the eye for cleaning, i.e., depositremoval. Therefore, increased surface hydrophilicity, and concomittentreductions in deposits of biological matter, allows increased wear time.

"Surface treatment processes", as used herein, refers to processes torender a surface more ophthalmically compatible, in which, by means ofcontact with a vapor or liquid, and/or by means of application of anenergy source (1) a coating is applied to the surface of an article, (2)chemical species are adsorbed onto the surface of an article, (3) thechemical nature (e.g., electrostatic charge) of chemical groups on thesurface of an article are altered, or (4) the surface properties of anarticle are otherwise modified.

There are a variety of methods disclosed in the art for rendering asurface of a material hydrophilic. For example, the lens may be coatedwith a layer of a hydrophilic polymeric material. Alternatively,hydrophilic groups may be grafted onto the surface of the lens, therebyproducing a monolayer of hydrophilic material. These coating or graftingprocesses may be effected by a number of processes, including withoutlimitation thereto, exposing the lens to plasma gas or immersing thelens in a monomeric solution under appropriate conditions.

Another set of methods of altering the surface properties of a lensinvolves treatment prior to polymerization to form the lens. Forexample, the mold may be treated with a plasma (i.e., an ionized gas), astatic electrical charge, irradiation, or other energy source, therebycausing the prepolymerzation mixture immediately adjacent the moldsurface to differ in composition from the core of the prepolymerizationmixture.

A preferred class of surface treatment processes are plasma processes,in which an ionized gas is applied to the surface of an article. Plasmagases and processing conditions are described more fully in U.S. Pat.Nos. 4,312,575 and 4,632,844, which are incorporated herein byreference. The plasma gas is preferably a mixture of lower alkanes andnitrogen, oxygen or an inert gas.

In a preferred embodiment, the lens is plasma treated in the presence ofa mixture of (a) a C₁₋₆ alkane and (b) a gas selected from the groupconsisting of nitrogen, argon, oxygen, and mixtures thereof. In a morepreferred embodiment, the lens is plasma treated in the presence of amixture of methane and air.

IV. UTILITY

A. Ophthalmic Lenses

The novel polymers or crosslinked polymers can be converted intoophthalmic moldings in a manner known in the art, in particular intocontact lenses, for example by carrying out the photopolymerization orphotocrosslinking of the novel polymers in a suitable contact lens mold.Examples of novel ophthalmic moldings, in addition to contact lenses,include without limitation thereto, contact lenses for visioncorrection, contact lenses for eye color modification, ophthalmic drugdelivery devices, ophthalmic wound healing devices, and the like.

B. Contact Lenses

A specific embodiment of the invention is directed to contact lenseswhich comprise essentially a novel polymer or polymeric network. Suchcontact lenses have a range of unusual and extremely advantageousproperties. Amongst these properties are, for example, their excellentcompatibility with the human cornea (if necessary after suitable surfacetreatment (coating)) and with tear fluid, which is based on a balancedratio between water content and water permeability, oxygen permeabilityand mechanical and adsorptive properties. This balance of desirableproperties results in high comfort and the absence of irritation andallergenic effects. Owing to their favorable permeability propertieswith respect to various salts, nutrients, water and diverse othercomponents of tear fluid and gases (CO₂ and O₂), the novel contactlenses have no effect, or virtually no effect, on the natural metabolicprocesses in the cornea. In contrast to many other siloxane-containingcontact lenses, the present innovative extended-wear lenses havechemical and mechanical properties and ion permeability sufficient toavoid the undesired binding effect. Furthermore, the novel contactlenses have high dimensional stability and shelf life.

It must be emphasized that this balance of properties, especially thehigh ion permeability in combination with the high oxygen permeability,is key to producing a true extended-wear contact lens. The high oxygenpermeability is required to prevent corneal swelling, thereby reducingthe likelihood of ocular damage and wearer discomfort during periods ofextended wear. The high ion permeability enables the lens to move on theeye such that corneal health is not substantially altered and wearercomfort is acceptable during a period of extended, continuous contactwith ocular tissue and ocular fluids.

The preferred extended-wear contact lenses of the present invention arethose which are comfortable over the period of extended wear. If thelens diameter is too small, the eyelids will not cover any portion ofthe lens when the eye is open. Thus, the eyelids will contact the edgeof the lens each time the eyelid is closed. This repeated eyelid-lensinteraction typically causes irritation, wearer discomfort, and lensdislodgement. Accordingly, the preferred contact lens diameters arethose which are sufficiently large to minimize eyelid-lens interactionand the associated irritation. Preferably, the contact lens has adiameter of about 12 to about 16 millimeters, more preferably about 13to 15 mm, and most preferably about 13.5 to 14.8 mm.

V. METHODS OF USE AS EXTENDED-WEAR LENSES

The above-described ophthalmic lenses have special utility asextended-wear contact lenses. Contact lenses having sufficient oxygenand water transmission rates from inner (base curve) to outer (frontcurve) surface may be continuously worn for long periods of time withoutsubstantial cornea swelling or wearer discomfort. The method of wearincludes (a) applying the lens to the eye and (b) allowing the lens toremain in intimate contact with the eye and tear fluids for a period ofat least 24 hours without substantial adverse impact on cornea health orwearer comfort.

A preferred method includes additional steps of (c) removing the lensfrom the ocular environment; (d) treating the lens (i.e., disinfectingor cleaning the lens); (e) re-applying the lens to the eye; and (f)allowing the lens to remain in intimate contact with the eye and tearfluids for a period of at least an additional 24 hours withoutsubstantial adverse impact on corneal health or wearer comfort.

In a preferred embodiment, the lens is worn for a continuous period ofat least four (4) days without substantial corneal swelling or wearerdiscomfort. In another preferred embodiment, the lens is worn for acontinuous period of at least seven (7) days without substantial cornealswelling or wearer discomfort. In another preferred embodiment, the lensis worn for a continuous period of at least 14 days without substantialcorneal swelling or wearer discomfort. In yet another preferredembodiment, the lens is worn for a continuous period of at least 30 dayswithout substantial corneal swelling or wearer discomfort

VI. METHODS OF MANUFACTURE

The ophthalmic lens may be manufactured, generally, by thoroughly mixingthe oxyperm and ionoperm polymerizable materials, applying anappropriate amount of the mixture to a lens mold cavity, and initiatingpolymerization. Photoinitiators, such as those commercially availablephotoinitiators disclosed above, may be added to the prepolymerizationmixture to aid in initiating polymerization. Polymerization may beinitiated by a number of well known techniques, which, depending on thepolymerizable material, may include application of radiation such asmicrowave, thermal, e-beam and ultraviolet. A preferred method ofinitiating polymerization is by application of ultraviolet radiation.

It has been discovered that the ion and/or water permeability of some ofthe aforementioned core materials may be increased by initiating andcompleting polymerization in an atmosphere which is substantially freeof oxygen. Suitable gases which are readily commercially availableinclude, without limitation thereto, nitrogen and carbon dioxide. Thus,in a preferred embodiment, the oxyperm and ionoperm polymerizablematerials are polymerized in an atmosphere having less than about 10000ppm oxygen. More preferably, the atmosphere surrounding thepolymerizable material contains less than about 1000 ppm oxygen. Evenmore preferably, the surrounding atmosphere contains less than about 100ppm oxygen, while the most preferred oxygen content is less than about20 ppm.

In the aforementioned embodiment, the prepolymer mixture must bedegassed prior to polymerization. The degassing may be accomplished by anumber of techniques known in the art. One technique for degassing theprepolymer mixture involves the use of a series of freezing and thawingsteps which are repeated until the appropriate gas concentration levelis achieved in the prepolymer mixture. This freeze/thaw method involvescooling the prepolymer mixture until the mixture solidifies, applying avacuum to the solidified prepolymer mixture, discontinuing the vacuum,and thawing the prepolymer mixture until the mixture is again in liquidform. While this degassing technique is advantageous in a laboratorysetting, other degassing techniques known in the art may be moreadvantageous for commercial lens manufacturing processes.

Alternatively, the atmosphere surrounding the lens mold may includeoxygen, under certain conditions. For example, if the lens mold halvesseal adequately to one another and the lens mold material has a low rateof oxygen permeability (e.g., polypropylene), it is possible topolymerize a degassed prepolymer mixture in a mold surrounded by ambientair without reaching prepolymer oxygen concentrations sufficiently highto substantially reduce ion or water permeability of the final lens.Thus, in another preferred embodiment of double-sided molding, the lensis formed by the following steps: (1) the prepolymer mixture isdegassed, (2) a lens mold half is filled with the prepolymer mixture,(3) the mold halves are sealed to one another, and (4) thepolymerization is initiated to form the lens, where the lens mold halvesare formed from a material having a low oxygen permeability and steps(2)-(4) may occur in the presence or absence of oxygen. In thisembodiment, it is preferred that the lens molds are stored in an inertsubstantially oxygen-free atmosphere, e.g., nitrogen or carbon dioxide,prior to use.

An essential feature of the manufacturing methods of the presentinnovative lenses is that a balance of high oxygen permeability and highion permeability is achieved. Manufacturing techniques and conditionswhich result in lowering either the oxygen permeability or the ionpermeability below levels sufficient to maintain good corneal health andon-eye movement during periods of extended wear are unacceptable toproduce the innovative extended-wear contact lenses of the presentinvention.

Preferably, the manufacturing method produces a contact lens having aDk/t of at least 70 barrers/mm and a Ionoton Ion PermeabilityCoefficient of at least 0.2×10⁻⁶ cm² /sec. More preferably, themanufacturing method produces a contact lens having a Dk/t of at least75 barrers/mm and a Ionoton Ion Permeability Coefficient of at least0.3×10⁻⁶ cm² /sec. The manufacturing method preferably provides acontact lens having a Dk/t of at least 87 barrers/mm and a Ionoton IonPermeability Coefficient of at least 0.4×10⁻⁶ cm² /sec.

The previous disclosure will enable one having ordinary skill in the artto practice the invention. In order to better enable the reader tounderstand specific embodiments and the advantages thereof, reference tothe following examples is suggested. However, the following examplesshould not be read to limit the scope of the invention.

Examples A-D are arranged in accordance with the materials definedabove. Thus, Examples A-1, A-2, etc. relate to Material "A" as definedabove, Examples B-1, B-2, etc. relate to Material "B" as defined above,Examples C-1, C-2, etc. relate to Material "C", and Examples D-1, D-2,etc. relate to Material "D". Temperatures are stated in degrees Celsiusunless otherwise specified.

Examples E, F and G are directed to demonstrating a correlation betweenon-eye movement and the Ionoton Ion Permeability Coefficient, theIonoflux Ion Permeability Coefficient, and the Hydrodell WaterPermeability Coefficient, respectively.

EXAMPLE A-1

A polysiloxane macromer is prepared by reacting, at room temperature(about 21 C.), one mole equivalent (about 100 grams) ofpoly(dimethylsiloxane)dialkanol (Shin Etsu Chemical Co., Tokyo, Japan)having hydroxyethyl propoxy end groups with 2 mole equivalents (about21.2 grams) of isophorone diisocyanate (Aldrich Chemical Co., Milwaukee,Wis.) in the presence of about 0.2 grams dibutyltin dilaurate catalyst(Pfaltz & Bauer, Inc., Waterbury, Conn.). After about 48 hours reactiontime, 2.02 mole equivalents (about 38.7 grams) of poly(ethylene glycol)("PEG", about 610 g/mol Mn, Dow Chemical Corp., Midland, Mich.) andabout 0.17 grams of dibutyltin dilaurate (about 0.43% by weight PEG) areadded to 80 grams of the reaction product from the prior step.Sufficient chloroform (Aldrich Chemical Co.) is added to the mixture tomake the mixture homogeneous. This mixture is stirred at roomtemperature for about 15 hours. Next, the mixture is stirred for about 8hours at a temperature of about 44 to 48 C., with the temperature heldsubstantially constant by a surrounding oil bath. The chloroform is thenevaporated, in order to achieve a final concentration of about 50% byweight solids, by stirring the mixture at room temperature for about 8hours. Then, about 2.14 mole equivalents (about 10.4 grams) ofisocyanatoethyl methacrylate ("IEM", Monomer Polymer, Inc.,Feasterville, Pa.) is added to the mixture. Finally, the mixture iscovered with aluminum foil and stirred at room temperature for about 17hours, yielding a polysiloxane-containing macromer having anumber-average molecular weight (Mn) of about 4000 grams per mole.

The macromeric solution is then polymerized, in the presence of about0.5 weight percent DAROCUR® 1173 photoinitiator (Ciba-Geigy Corporation,Ardsley, N.Y.) to form contact lenses. Polypropylene contact lens moldsare filled with the copolymer precursor solution. Ultraviolet light(about 300 to 400 nm) at about 3-6 mW/cm² is applied to the solution inthe mold for about 3 hours at room temperature. The UV light, inconjunction with the photoinitiator, causes polymerization, therebyallowing the solution to form a contact lens having the shape of themold. The lenses are extracted with isopropanol to remove the remainingchloroform solvent and any unreacted components. The product is apolysiloxane-containing polymeric contact lens.

Prior to taking oxygen permeability measurements, the lenses arehydrated by placing the lenses in isotonic buffered saline solution forat least eight hours. After hydration, if necessary because of handling,each lens is cleaned with MIRAFLOW® Daily Cleaner (CIBA VisionCorporation, Duluth, Ga.) to remove grease and lipids prior to testing.Excess MIRAFLOW® cleaner is removed by rinsing with saline or purifiedwater.

Oxygen fluxes (J) are measured at 34 C in a wet cell (i.e., gas streamsare maintained at about 100% relative humidity) using a Dk 1000instrument. Oxygen transmissibility, D_(k) /t, is determined as outlinedin the portions of the specification relating to oxygen permeability andtransmissibility.

EXAMPLE A-2

A polysiloxane macromer is first prepared substantially in accordancewith the procedure described in Example A-1.

A copolymer precursor solution is prepared by mixing about 180 gramspolysiloxane-containing macromer, about 15 grams3-methacryloxypropyltris (trimethylsiloxy)silane (Shin Etsu), about 4grams 2-hydroxyethyl methacrylate ("HEMA"), about one gram ethyleneglycol dimethacrylate ("EDGMA"), and about one gram DAROCUR® 1173photoinitiator at room temperature for about 16 hours.

The copolymer precursor solution is then polymerized to form contactlenses. Polypropylene contact lens molds are filled with the copolymerprecursor solution. Ultraviolet light (about 300 to 400 nm) at about 3-6mW/cm² is applied to the solution in the mold for about 3 hours at roomtemperature. The UV light causes polymerization, thereby allowing thesolution to form a contact lenses having the shape of the mold. The lensare extracted with isopropanol to remove remaining chloroform solventand any unreacted components. A preferred resulting polymer containsabout 81.8 weight percent polysiloxane macromer, about 13.6% TRIS, about3.6% 2-hydroxyethyl methacrylate, and about 0.9% EDGMA.

The contact lens is degassed by placing the lens under suitable vacuumfor a period sufficient to remove substantially all gas from the lensmatrix. Fully hydrated degassed contact lenses having this compositionhave a Dk of about 87 barrers, a water content of about 19 weightpercent, and a modulus of elasticity of about 2.5 MPa

EXAMPLE A-3

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2, but having the final composition ofabout 19.5 weight percent polysiloxane macromer, about 47% TRIS, andabout 33.5% N,N-dimethylacrylamide. Fully hydrated contact lenses havingthis composition have a Dk of about 49 barrers, a water content of about30 weight percent, and a modulus of elasticity of about 2.4 MPa.

EXAMPLE A4

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2, but having the final composition ofabout 30 weight percent polysiloxane macromer, about 50% TRIS, and about20% N,N-dimethylacrylamide. Fully hydrated contact lenses having thiscomposition have a Dk of about 76 barrers, a water content of about 20weight percent, and a modulus of elasticity of about 1.3 MPa.

EXAMPLE A-5

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2, but having the final composition ofabout 30 weight percent polysiloxane macromer, about 40% TRIS, and about30% N,N-dimethylacrylamide. Fully hydrated contact lenses having thiscomposition have a Dk of about 55 barrers, a water content of about 30weight percent, and a modulus of elasticity of about 3.5 MPa

EXAMPLE A-6

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2, but having the final composition ofabout 30 weight percent polysiloxane macromer, about 60% TRIS, and about10% N,N-dimethylacrylamide. Fully hydrated contact lenses having thiscomposition have a Dk of about 110 barters, a water content of about 8.7weight percent, and a modulus of elasticity of about 2.6 MPa

EXAMPLE A-7

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2, but having the final composition ofabout 30 weight percent polysiloxane macromer and about 70% TRIS. Fullyhydrated contact lenses having this composition have a Dk of about 128barrers and a water content of about 4.9 weight percent.

EXAMPLE A-8

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2, but having the final composition ofabout 30 weight percent polysiloxane macromer, about 45% TRIS, 5%fluoroacrylate, and about 20% N,N-dimethylacrylamide. Fully hydratedcontact lenses having this composition have a Dk of about 69 barrers, awater content of about 20 weight percent, and a modulus of elasticity ofabout 1.4 MPa.

EXAMPLE A-9

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2, but having the final composition ofabout 82 weight percent polysiloxane macromer, about 14.4% TRIS, andabout 3.7% 2-hydroxyethyl methacrylate. Fully hydrated contact lenseshaving this composition have a Dk of about 96 barrers, a water contentof about 19 weight percent, and a modulus of elasticity of about 1.8MPa.

EXAMPLE A-10

A polysiloxane macromer is prepared substantially in accordance with theprocedures described in Example A-1, but the polyethylene glycol has amolecular weight of about 660.

A contact lens is prepared substantially in accordance with theprocedure described in Example 2, but having the final composition ofabout 81.9 weight percent polysiloxane macromer, about 13.6% TRIS, about3.7% 2-hydroxyethyl methacrylate, and about 0.8% ethylene glycoldimethacrylate. Fully hydrated contact lenses having this compositionhave a Dk of about 81 barrers, a water content of about 20 weightpercent, and a modulus of elasticity of about 1.4 MPa

EXAMPLE A-11

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2, but having the final composition ofabout 82 weight percent polysiloxane macromer, about 8.6% TRIS, about4.9% fluoroacrylate, about 3.5% 2-hydroxyethyl methacrylate, and about1% EDGMA. Fully hydrated contact lenses hating this composition have aDk of about 77 barrers, a water content of about 22 weight percent, anda modulus of elasticity of about 1.3 MPa

EXAMPLE A-12

A contact lens is prepared substantially in accordance with theprocedure described in Example A-1, but the polysiloxane macromer usedhas hydroxy-sec-butyl end groups as opposed to hydroxyethylpropoxy endgroups. The fully hydrated contact lens, after degassing, has a Dk ofabout 70 barrers, about a 22 weight percent water content, and a modulusof elasticity of about 2.4 Mpa.

EXAMPLE B-1 Macromer synthesis

51.5 g (50 mmol) of the perfluoropolyether Fomblin® ZDOL (from AusimontS.p.A, Milan) having a mean molecular weight of 1030 g/mol andcontaining 1.96 meq/g of hydroxyl groups according to end-grouptitration is introduced into a three-neck flask together with 50 mg ofdibutyltin dilaurate. The flask contents are evacuated to about 20 mbarwith stirring and subsequently decompressed with argon. This operationis repeated twice. 22.2 g (0.1 mol) of freshly distilled isophoronediisocyanate kept under argon are subsequently added in a counterstreamof argon. The temperature in the flask is kept below 30° C. by coolingwith a waterbath. After stirring overnight at room temperature, thereaction is complete. Isocyanate titration gives an NCO content of 1.40meq/g (theory: 1.35 meq/g).

202 g of the α,ω-hydroxypropyl-terminated polydimethylsiloxane KF-6001from Shin-Etsu having a mean molecular weight of 2000g/mol (1.00 meq/gof hydroxyl groups according to titration) are introduced into a flask.The flask contents are evacuated to approx. 0.1 mbar and decompressedwith argon. This operation is repeated twice. The degassed siloxane isdissolved in 202 ml of freshly distilled toluene kept under argon, and100 mg of dibutyltin dilaurate (DBTDL) are added. After completehomogenization of the solution, all the perfluoropolyether reacted withisophorone diisocyanate (IPDI) is added under argon. After stirringovernight at room temperature, the reaction is complete. The solvent isstripped off under a high vacuum at room temperature. Microtitrationshows 0.36 meq/g of hydroxyl groups (theory 0.37 meq/g). 13.78 g (88.9mmol) of 2-isocyanatoethylmethacrylate (IEM) are added under argon to247 g of the α,ω-hydroxypropyl-terminatedpolysiloxane-perfluoropolyether-polysiloxane three-block copolymer (athree-block copolymer on stoichiometric average, but other block lengthsare also present). The mixture is stirred at room temperature for threedays. Microtitration then no longer shows any isocyanate groups(detection limit 0.01 meq/g). 0.34 meq/g of methacryl groups are found(theory 0.34 meq/g).

The macromer prepared in this way is completely colourless and clear. Itcan be stored in air at room temperature for several months in theabsence of light without any change in molecular weight.

EXAMPLE B-2 Macromer synthesis

The first step of the macromer synthesis described under Example B-1 isrepeated. An isocyanate titration of the perfluoropolyether reacted withIPDI gives a content of 1.33 meq/g of NCO (theory 1.35 meq/g).

In a second step, 87.1 g of the α,ωhydroxypropyl-terminatedpolydimethylsiloxane TegomerH-Si2111 (Th. Goldschmidt AG, Essen) havinga mean molecular weight of 890 g/mol (2.25 meq/g of hydroxyl groupsaccording to titration) are dissolved in 87 ml of toluene. After thereaction has been carried out as indicated under B-₁ and the solvent hasbeen removed, a hydroxyl group content of 0.66 meq/g is determined bymicrotitration (theory 0.60 meq/g). The resultant intermediate is inturn reacted with a stoichiometric amount of isocyanatoethylmethacrylate. Microtitration then no longer shows any isocyanate groups(detection limit 0.01 meq/g). 0.56 meq/g of methacryl groups are found(theory 0.53 meq/g). The macromer prepared in this way is completelycolourless and clear and has a long shelf life.

EXAMPLE B-3 Macromer synthesis

The first step of the macromer synthesis described under Example B- 1 isrepeated, but using a different perfluoropolyether: Fomblin® ZDOLTX(from Ausimont S.p.A., Milan). This material is terminated by O--CF₂--CH₂ --(OCH₂ CH₂)_(n) --OH (where n=0, 1 or 2). The material used has amean molecular weight of 1146 g/mol, and contains 1.72 meq/g of hydroxylgroups according to end-group analysis. An isocyanate titration of theperfluoropolyether reacted with IPDI shows a content of 1.23 meq/g ofNCO (theory 1.25 meq/g).

In the second step, a stoichiometric amount of Tegomer Hi-Si2111 andtoluene are again added. After the reaction has been carried out asindicated under Example B-1 and the solvent has been removed, a hydroxylgroup content of 0.63 meq/g is determined by microtitration (theory 0.58meq/g). The resultant intermediate is in turn reacted with astoichiometric amount of isocyanatoethyl methacrylate. Microtitrationthen no longer shows any isocyanate groups (detection limit 0.01 meq/g).0.55 meq/g of methacryl groups are found (theory 0.51 meq/g). Themacromer prepared in this way is completely colourless and clear and hasa long shelf life.

EXAMPLE B4 Macromer synthesis

The first step of the macromer synthesis described under Example B-1 isrepeated, but 5.0 g of Fomblin/ZDOL and 2.18 g of IPDI are employed.When the reaction is complete, microtitration shows an isocyanate groupcontent of 1.31 meq/g of hydroxyl groups (theory 1.36 meq/g).

The second step of the synthesis described under Example B-1 is likewisecarried out analogously, the stoichiometric ratio betweenisocyanate-terminated perfluoropolyether and hydroxypropyl-terminatedpolysiloxane being 2:3. After the reaction has been completed and thesolvent has been removed, microtitration shows a content of 0.2 meq/g ofhydroxyl groups (theory 0.1 8 meq/g).

The third step of the synthesis described under Example B-1 is likewisecarried out analogously, IEM being employed in a preciselystoichiometric ratio. After the reaction, free isocyanate groups can nolonger be detected (detection limit 0.01 meq/g). 0.19 meq/g of methacrylgroups are found (theory 0.19 meq/g).

EXAMPLE B-5 Production of contact lenses

13.0 g of macromer from Example B-1 are dissolved in 5.6 g of ethanol(Fluka, puriss. p.a.) (70% by weight solution). After completehomogenization of the solution, 5.2 g of3-tris(trimethylsiloxy)silylpropyl methacrylate (TRIS from Shin-Etsu,product No. KF-2801), 7.8 g of freshly distilled dimethylacrylamide(DMA) and 160 mg of photoinitiator Darocur® 1173 (Ciba) are added. Thissolution is filtered through a Teflon membrane having a pore width of0.45 mm under an argon pressure of from 1 to 2 atm. The filteredsolution is frozen in a flask in liquid nitrogen, the flask is evacuatedunder a high vacuum, and the solution is returned to room temperaturewith the flask sealed. This degassing operation is repeated twice. Theflask containing the macromer/comonomer solution is then transferredinto a glove box with an inertgas atmosphere, where the solution ispipetted into dust-free contact-lens moulds made from polypropylene. Themoulds are closed, and the polymerization reaction is effected by UVirradiation (15 mW/cm2, 5 min.), with simultaneous crosslinking. Themoulds are then opened and placed in ethanol, causing the resultantlenses to swell out of the moulds. The lenses are extracted for 24 hourswith constantly replenished distilled dichloromethane and subsequentlydried in a high vacuum. The dried lenses are equilibrated inphosphate-buffered physiological saline solution in autoclave-resistantvials and then autoclaved at 120° C. for 30 minutes. All physical datameasurements are carried out on autoclaved lenses.

The lenses produced in this way are characterized by the followingvalues: oxygen permeability (Dk) 77 barrer (determined by the "wet"method described below), water content of the equilibrated lenses 32percent by weight, elongation at break at 35° C. 360%, modulus ofelasticity 30° C. 0.5 MPa (measured using a Minimat from PolymerLaboratories, UK).

"Wet" measurement of the oxygen permeability

The oxygen permeability of a material is determined by the coulometricmethod. To this end, pre-autoclaved lenses are clamped in a holder andthen covered on the upper side with a 2 cm layer of water. A gas mixturecomprising 21% of oxygen and 790% of nitrogen is passed continuouslythrough the water layer with swirling. The oxygen which diffuses throughthe lens is measured using a coulometric detector. The reference valuesare those measured on commercially available contact lenses using thismethod. Cibasoft® (CIBA-Vision, HEMA lens) gives a measurement ofapprox. 7-10 barrer, and Excelens® (CIBA-Vision, PVA lens) gives ameasurement of approx. 22 barrer.

Unfortunately, the oxygen permeability of, for example, contact lensesis frequently given in the literature as a straight Dk value withoutfurther definition and frequently without giving any reference material.These are usually values determined on dry material (dry measurement). Acomparative measurement of the oxygen permeability of polymer B-5 showsthe differences:

a) "wet" measurement: 77 barrer

b) dry measurement: 158 barrer

EXAMPLE B6

The process described under Example B-5 for the production of contactlenses is repeated, but the mixture of comonomers has the followingcomposition (in per cent by weight):

55% of macromer from Example B-1

22% of TRIS

22.5% of DMA

0.5% of Blemer® QA

EXAMPLE B-7

The process described under Example B-5 for the production of contactlenses is repeated, but the mixture of comonomers has the followingcomposition (in percent by weight):

55% of macromer from Example B-1

22% of TRIS

23% of DMA

EXAMPLE B-8

Analogously to EXAMPLE B-5 (in weight percent):

40% of macromer from Example B-1

30% of TRIS

30% of DMA

EXAMPLE B-9

The process described under B-5 for the production of contact lenses isrepeated, but a 70% by weight solution of the macromer in toluene isused instead of the 75% by weight solution in ethanol described above.The mixture of comonomers has the following composition (in percent byweight):

55% of macromer from Example B-1

22% of TRIS

23% of DMA

EXAMPLE B-10

The process described under B-5 for the production of contact lenses isrepeated, but a 70% by weight solution of the macromer inoctamethylcyclotetrasiloxane is used instead of the 75% by weightsolution in ethanol described above. The mixture of comonomers has thefollowing composition (in per cent by weight):

55% of macromer from Example B-1

22% of TRIS

23% of DMA

Physical measurement data for the contact-lens materials from ExamplesB-5 to B-10 (O₂ Dk value, wet method) are presented in TABLE B-I:

                  TABLE B-I                                                       ______________________________________                                                                    Modulus of                                                                            Elongation at                                     Water Content                                                                            Dk       Elasticity                                                                            Break                                     Example (%)        (barrer) (MPa)   (%)                                       ______________________________________                                        B-5     32         77       0.5     360                                       B-6     23.8       110      1.1     160                                       B-7     19.5       110      0.6     130                                       B-8     30.9       81       0.3     300                                       B-9     30                                                                     B-10   25                                                                    ______________________________________                                    

EXAMPLE B-11

About 10.0 grams of macromer from Example B-1 are dissolved in 3.3 gramsof ethanol (Fluka, puriss. p.a). After complete homogenization of thesolution, about 4.0 grams of 3-tris(trimethylsiloxy)silylpropylmethacrylate (TRIS, from Shin-Etsu, product no. KF-2801), about 5.9 g.freshly distilled dimethylacrylamide (DMA), about 0.1 g. Blemer® QA (amethacrylate having quaternary ammonium substituents, Linz Chemie) andabout 100 mg of photoinitiator Darocur® 1173 (Ciba) are added. Thesolution is filtered through a TEFLON membrane having a pore width of0.45 mm under an argon pressure of from about 1 to 2 atm.

The filtered solution is frozen in a flask in liquid nitrogen, the flaskis evacuated under a high vacuum, and the solution is returned to roomtemperature with the flask sealed. This degassing operation is repeatedtwice. The flask containing the macromer/comonomer solution is thentransferred into a glove box with an inert gas atmosphere, where thesolution is pipetted into dust-free, polypropylene contact lens molds.The molds are closed, and the polymerization reaction is effected by UVirradiation, with simultaneous crosslinking. The molds are then openedand placed in isopropyl alcohol, causing the resultant lenses to swellout of the molds. The lenses are extracted for about 24 hours withnearly continuous replenishing of isopropyl alcohol. Subsequently, thelenses are dried under high vacuum.

The dried contact lenses are equilibrated in autoclave-resistant vialsin phosphate-buffered physiological saline solution, and then autoclavedfor 30 minutes at about 120° C. Physical measurement data for theautoclaved lens is presented below:

Dk barrer!: 93

water content %!: 20.3%

modulus of elasticity Mpa!: 0.96

EXAMPLE B-12

Lenses are prepared in accordance with the procedures described inExample B-11, but are subsequent surface treated as follows. The driedlenses are transferred into a plasma coating apparatus wherein they aresurface treated in a methane/"air" mixture ("air", as used here, denotes79% nitrogen and 21% oxygen) for a period of about 5 minutes. Theapparatus and plasma treatment process have been disclosed by H. Yasudain "Plasma Polymerization", Academic Press, Orlando, Fla. (1985), pages319 forward.

The plasma-treated contact lenses are equilibrated inautoclave-resistant vials in phosphate-buffered physiological salinesolution, and then autoclaved for 30 minutes at about 120° C. Physicalmeasurement data for the plasma-coated autoclaved lens is presentedbelow:

Dk barrer!: 88

water content %!: 21.8%

modulus of elasticity Mpa!: 1.03

EXAMPLE B-13

Lenses are prepared in accordance with the procedures described inExample B-5, but the mixture of comonomers has the followingcomposition, in weight percentages:

Macromer of Example B-1: 60%

TRIS: 25%

DMA: 15%

EXAMPLE B-14

Lenses are prepared in accordance with the procedures described inExample B-6, with the same comonomer composition, but the comonomers aredispensed into dust-free contact lens molds in ambient air atmosphere.

EXAMPLE C-1

Reaction of α,ω-bis-aminopropyl-dimethylpolysiloxane with D(+)gluconicacid d-lactone:

Before the reaction, the amino-functionalized polydimethylsiloxaneemployed for the synthesis (X-22-161-C, Shin Etsu, JP) was finelydispersed in acetonitrile, extracted and then subjected to moleculardistillation.

The following reactions take place with exclusion of H₂ O. 200 g ofpurified amino-functionalized polydimethylsiloxane (0.375 meq of NH₂ /g;Mn(VPO) 3400-3900 (VPO, Vapour Pressure Osmometry)), dissolved in 200 mlof absolute THF, are slowly added dropwise to a suspension of 13.35 g(75 mmol) of D(+)gluconic acid d-lactone in 50 ml of absolute THF andthe mixture is stirred at 40° C. for about 24 hours until the lactonehas reacted completely. (Monitoring of the reaction by thin layerchromatography (TLC): silica gel; i-propanol/H2O/ethyl acetate 6:3:1;staining with Ce(IV) sulfate/phosphoromolybdic acid solution (CPSreagent)). After the reaction, the reaction solution is concentrated todryness and the residue is dried under 3 Pa (0.03 mbar) for 48 hours.213.3 g of α,ω-bis(3-gluconamidopropyl)poly-dimethyl are obtained.Titration of the amino groups with perchloric acid shows a conversion ofthe amino groups of more than 99.8%.

Reaction of α,ω-bis-3-gluconamidopropyl-dimethylpolysiloxane with IEM

The product obtained above (213.3 g) is dissolved in 800 ml of absoluteTHF and the solution is heated to 40° C. with the addition of catalyticamounts of dibutyltin dilaurate (DBTDL). 14 g (90 mmol) of IEM in 20 mlof absolute THF are added dropwise to this solution over a period ofabout 4 hours. This corresponds to a concentration of 1.2 equivalents ofIEM per gluconamide unit. The reaction is carried out in the course of48 hours (monitoring of the reaction by IR spectroscopy detection of theNCO ties). The reaction solution is concentrated and the product isdried in a brown glass flask under 3 Pa (0.03 mbar) for 24 hours, whilecooling with ice. 227.2 g of a colourless rubber-elastic product of highoptical transparency remain.

EXAMPLE C-2 to C-7

Further amino propyl-dimethylpolysiloxanes (PDMS) are reacted with adifferent amount of gluconolactone and concentrations of IEM analogouslyto Example C-1 . The examples are summarized in Table C-I

                  TABLE C-I                                                       ______________________________________                                                           Amount of batch                                                                     PDMS                                                                          g       Glu   IEM                                    Ex-   Poly(dimethyl siloxane) (PDMS)                                                                   (mmol   g     g                                      ample Name      Type   Mn   NH.sub.2 *                                                                         of NH.sub.2)                                                                        (mmol)                                                                              (mmol)                           ______________________________________                                        C-1   X-22-161-C                                                                              term.  3400 2    200   13.4  14.0                                                              (75)  (75)   (90.0)                          C-2   X-22-161-C                                                                              term.  3400 2    200   13.4  25.7                                                              (74)  (75)  (165.0)                          C-3   X-22-161-C                                                                              term.  3400 2    200   13.4  29.2                                                              (75)  (75)  (187.5)                          C-4   PS 813    pen.   1200 1                                                 C-5   GP 4      pen.   3150 2.6                                               C-6   GP 6      pen.   5960 3                                                 C-7   KF 8003   pen.   9700 4.7  200   17.5  18.2                                                              (98)  (98)  (117.4)                          ______________________________________                                    

Legend

X-22-161-C and KF 8003 are products from Shin Etsu (Japan), PS813 is aproduct from Petrarch-H ls, GP4 and GP6 are products from Genesee.

* Amino groups per macromer chain

Glu:D(+) gluconic acid d-lactone

term: terminal

pen: pendent

EXAMPLE C-8

The reaction is carried out in accordance with Example C-1, but insteadof D(+)gluconic acid d-lactone, 75 mmol of lactobionic acid 1,5-lactone,suspended in 50 ml of absolute THF, are added dropwise to a solution ofamino-functionalized polydimethylsiloxane (X-22-161-C) in 180 ml ofabsolute THF and 20 ml of DMSO (pure, 99%). Titration of the aminogroups with perchloric acid indicates a reaction conversion of 99%(<0.01 meq of NH2/g). Here also, a colourless optically clear macromeris obtained.

EXAMPLE C-9 and C-10

The reactions are carried out analogously to Example C-1. However, thecatalyst necessary for addition of the isocyanate onto the hydroxylgroups is varied. Instead of DBTDL, catalytic amounts of1,4-diazabicyclo(2.2.2)octane (DABCO) or 4 dimethylamino-pyridine (DMAP)are added and the reaction is continued as described under Example C-1.In both cases, an optically clear, colourless rubber-elastic macromerresults in a manner corresponding to Example C-1.

EXAMPLE C-11

The reaction is carried out analogously to Example C-1 . In a mannercorresponding to Example C-8, 0.1 mol of lactobionic acid 1,5-lactone issuspended in 50 ml of absolute THF and the suspension is added dropwiseto a solution of amino-functionalized polydimethylsiloxane (KF-8003) in180 ml of absolute THF and 20 ml of DMSO (pure, 99%). The reaction timeis increased to about 48 hours. A residual content of 0.07 meq of NH₂ /gcan be detected, and is reacted completely by addition of thecorresponding molar amount of D(+)gluconic acid d-lactone to thereaction solution. The colourless highly transparent product has aresidual content of amino groups of <0.01 meq/g.

EXAMPLE C-12

52.09 g (9.78 mmol) of purified amino-functionalizedpolydimethylsiloxane (X-22-161-C, Shin Etsu JP), dissolved in 110 ml ofabsolute THF, are initially introduced into the reaction vessel under aninert gas atmosphere, and 1.14 g (6.52 mmol) ofD-glucaro-1,4:6,3-dilactone, dissolved in 20 ml of absolute THF, areadded. The reaction solution is stirred at room temperature for 15 hoursand then worked up in a manner corresponding to Example C-1. The aminecontent is 0.134 meq/g. The terminal amino groups of the resultingpenta-block macromer are reacted with gluconolactone in the followingreaction step. 41.84 g (5.146 meq of NH2) of the above macromer and0.917 g (5.15 mmol) of D(+)gluconic acid d-lactone are suspended in 300ml of absolute THF and the suspension is stirred under nitrogen at 40°C. for 18 hours. The filtered solution is then concentrated and theresidue is dried under 3 Pa (0.03 mbar) for 48 hours. A highly viscousoptically clear substance having a residual content of amino groups of0.013 meq/g results.

EXAMPLE C-13

Preparation of an amino- and perfluoroalkyl-functionalizedpolydimethylsiloxane

3.0 ml of absolute toluene are added to 15 g ofpoly(dimethylsiloxane-co-methylhydrosiloxane) (Bayer Silopren U-230;10,000 g/mol; 2.3 mmol of Si--H/g), and 1.72 g (9.2 mmol) ofallylphthalimide CAS Reg. No. 5428-09-1! are then added. The mixture isfrozen several times and the flask evacuated and then brought to roomtemperature again. The flask is then let down with argon. 0.7 ml of a0.005 molar solution of Lamoreaux catalyst (prepared in accordance withU.S. Pat. No. 3,220,972, General Electric) in absolute toluene (100 ppmof Pt/mol of Si--H) is added and the mixture is heated to 80° C. After areaction time of half an hour, a colourless, clear to slightly cloudysolution, the 1H-NMR spectrum of which no longer shows resonances ofallylic hydrogen atoms, is obtained.

Thereafter, 6.2 g (15.3 mmol) of degassed allyl1H,1H,2H,2H-perfluorooctyl ether are slowly added and the mixture isstirred at 80° C. for 2 hours. A 1H-NMR spectrum now shows a severelyweakened resonance of the Si--H function at 4.6 ppm and an intenseresonance at 0.5 ppm, which originates from Si--CH₂ hydrogen atoms.

3.0 ml of 1-hexene are then added in order to react the remaining excessof Si--H groups, which could otherwise cause crosslinking of the polymerwhen air later has access. The mixture is further stirred at 80° C. foranother half an hour. The reaction mixture is then left to standovernight. The product is purified over a silica gel column withhexane/ethyl acetate (3:2), the solvent is stripped off and the macromeris dried under a high vacuum. A colourless, clear, viscous product isobtained. The macromer purified in this way is taken up in 20 ml ofhexane 20 ml of methylamine (33% in ethanol) are added and the mixtureis heated to 40° C. After 10-15 minutes, a white voluminous precipitateseparates out. After 30 minutes, the suspension is cooled and filteredand the precipitate is washed with a little hexane. The filtrate isevaporated and the residue is then dried under a high vacuum.Thereafter, the content of amino groups is determined by titrimetry(perchloric acid).

The resulting macromer is clear and viscous. The amino group content is78.6% of theory. The total yield of macromer after the chromatographicpurification is 75%.

Preparation of a gluconamide

17.3 g (corresponding to an amine content of 5.4 meq) of thisaminoalkyl-substituted product are dissolved in 20 ml of dried THF. Thesolution is repeatedly frozen, degassed and let down with argon. All thefollowing operations are carried out in an argon atmosphere. 712 mg ofD(+)-gluconic acid d-lactone (4 mmol) are then added. Because of the lowsolubility of the lactone, a suspension is initially obtained. Afterstirring overnight at 50° C., the solution is clear and the lactone hasbeen used completely. The stoichiometric remaining amount ofD(+)-gluconic acid d-lactone (260 mg, 1.46 mmol) is then added and themixture is stirred again at 50° C. overnight. A trace of unreactedlactone is observed. Completion of the reaction is monitored by means ofthin layer chromatography on silica gel plates with the mobile phase1-propanol/ethyl acetate/water (6:1:3). The silica gel plates aredeveloped by means of Ce(IV) sulfate/phosphoromolybdic acid solution.Subsequent titration on amino groups yields a residual amino content of<0.1%. After filtration and removal of the solvent by distillation, ahighly viscous clear macromer with 0.295 mequivalent of gluconamide pergram of macromer is obtained.

EXAMPLE C-14

Before the polymerization, the acrylates employed, isobutyl acrylate(IBA), N,N-dimethylacrylamide (DMA) and3-methacryloyloxypropyl-tris(trimethylsilyloxy)silane (TRIS) are eachfreed from inhibitors by distillation. 0.32 g (2.76 mmol) of IBA, 0.80 g(8.1 mmol) of DMA and 1 .44 g (3.4 mmol) of TRIS are weighed into a 50ml round-bottomed flask and the flask is flushed with N2 for half anhour, while cooling with ice. 1.44 g of macromer from Example C-1 aretransferred to a round-bottomed flask with a nitrogen attachment,degassed under 3 Pa (0.03 mbar) for 24 hours and then dissolved in 2.7 gof ethanol which has been flushed with N2 for half an hour beforehand.The subsequent preparation of samples and the polymerization are carriedout inside a glove box with exclusion of oxygen. The above monomermixture and the macromer solution from Example C-1 are mixed, with theaddition of 0.012 g (0.21 mmol) of Darocur® 1173 and the mixture issubjected to microfiltration (0.45 mm filter). 180 μl of this mixtureare introduced into a polypropylene mould, which is then closed with anappropriate lid of polypropylene. The mixture is then irradiated with aUV-A mercury high pressure lamp in a nitrogen atmosphere in a UV ovenequipped for this for 5 minutes. The lamps (5 each of the brandTLK40W/10R, Philips) are above and below the holder inserted. Theirradiation intensity is 14.5 mW/cm2.

The polypropylene mould is opened and the finished discs or lenses areremoved by soaking by means of a solvent mixture of methylene chlorideand ethanol (2:3). The lenses and discs are extracted in ethanol at roomtemperature in special polypropylene cages for 48 hours and then driedat 40° C. under 10 Pa (0.1 mbar) for 24 hours (autoclaving at 120° C.,30 minutes). The discs show an E modulus of 1.1 MPa, a permeability tooxygen of 183 barrier and a hardness (Shore A) of 53.

EXAMPLE C-15 to C-19

Further polymers are prepared in a manner corresponding to Example C-14(composition in percentages by weight). Table C-II shows examples C-15to C-19 and the properties of the resulting materials measured on discs.

                                      TABLE C-II                                  __________________________________________________________________________          Water Macromer                                                                            Macromer                                                                            DMA  DMEA TRIS E                                            Content                                                                             from  weight                                                                              weight                                                                             weight                                                                             weight                                                                             modulus                                                                             Dk                               Example                                                                             (%)   Example                                                                             percent                                                                             percent                                                                            percent                                                                            percent                                                                            (Mpa) (barrer)                         __________________________________________________________________________    C-15  not   C-3   32.8  --   30   37.2 --    --                                     measured                                                                C-16  19.9  C-3   32.9  34.3 --   32.7 0.7   84                               C-17  25.1  C-3   39.3  34.3 --   36.4 0.9   72                               C-18  17.5  C-3   35.7  34.3 --   30.0 0.7   100                              C-19  23.4  C-3   33.3  33.3 --   33.4 0.7   96                               __________________________________________________________________________

Legend

DMA: N,N-Dimethylacrylamide

TRIS: 3-Methacryloyloxypropyl-tris(trimethylsilyloxy)silane

DMEA: 2-Dimethylaminoethyl acrylate

EXAMPLE C-20 Uncoated contact lens

A contact lens is prepared in a manner corresponding to Example C-14,using the Example C-3 macromer, with the following composition inpercentages by weight:

Macromer: 33.3

DMA: 33.3

TRIS: 33.4

The lens has a Dk of about 94 and a water content of about 20.0 weightpercent. The results are presented in TABLE C-III for comparision withcoated lens properties.

EXAMPLE C-21 Plasma-treated contact lens

Dried lenses prepared in accordance with the procedures described inExample C-20 are transferred-into a plasma coating apparatus where thelenses are surface treated in a methane/"air" mixture ("air", as usedhere, denotes 79% nitrogen and 21% oxygen). The apparatus and plasmatreatment process have been disclosed by H. Yasuda in "PlasmaPolymerization", Academic Press, Orlando, Fla. (1985), pages 319forward.

The dried plasma-treated contact lenses are equilibrated inautoclave-resistant vials in phosphate-buffered physiological salinesolution, and then autoclaved for 30 minutes at about 120° C. Theplasma-treated autoclaved lens has a Dk barrer! of 90 and a watercontent of 21.5%. The results are presented in TABLE C-III forcomparision with coated lens properties.

                  TABLE C-III                                                     ______________________________________                                        Example Surface type                                                                              Dk (barrer)                                                                              Water content (%)                              ______________________________________                                        C-20    untreated   94         20.0                                           C-21    plasma-treated                                                                            90         21.5                                           ______________________________________                                    

EXAMPLE C-22

The synthesis of this polymer corresponds to Example C-14 with thefollowing comonomer composition: Example C-3 macromer/TRIS/DMA:32.8%/32.6%/34.2% (in percentages by weight) and an addition of 0.4% byweight of trimethylammonium-2hydroxypropyl methacrylate hydrochloride(Blemer® QA, Nippon Oil Corp.). The polymer has a modulus of 0.9 MPa anda permeability to oxygen of 82 barrer. The water content is 25.1% (after30 minutes' autoclaving at 120° C.). For comparison, Example C-16 has awater content of 20% with a very similar comonomer composition (noaddition of Blemer® QA).

EXAMPLE C-23

The polymer is prepared analogously to Example C-14, but thepolymerization is carried out in bulk, which means without addition ofethanol. The composition of the comonomers and the material propertiesof the polymer synthesized, measured on discs is given below.

Example C-7 macromer: 41%

IBA: 23%

1-vinyl-2-pyrrolidone (NVP): 24%

acrylonitrile (AN): 12%

Hardness (shore A): 68

EXAMPLE C-24

The polymerization is carried out in accordance with Example C-14 butwith the following changed comonomer composition:

macromer of Example C-7/IBA/TRIS 20%/90%/60% and 1% (in percentages byweight) of bis(3-methacryloyloxypropyl)tetra methyldisiloxane.

An optically clear polymer with an E modulus of 0.4 MPa, a permeabilityto oxygen of 241 barrer and a hardness (Shore A) of 42 is obtained.

EXAMPLES C-25 through C-27

Contact lenses are prepared in accordance with the procedure describedin Example C-14. The compositions in weight percentages are as follows:

    ______________________________________                                                        Macromer IBA   DMA   TRIS  HFBA                                               weight   weight                                                                              weight                                                                              weight                                                                              weight                             Example                                                                              Macromer percent  percent                                                                             percent                                                                             percent                                                                             percent                            ______________________________________                                        C-25   C-3      36.0     8.0   20.0  36.0  --                                 C-26   C-2      35.0     5.0   20.0  35.0  5.0                                C-27   C-3      32.8     --    30.0  37.2  --                                 ______________________________________                                    

where

IBA is isobutylacrylate,

DMA is N,N-Dimethylacrylamide

TRIS is 3-methacryloyloxypropyl-tris(trimethylsiloxy)silane

HFBA is 2,2,3,4,4,4,-hexafluorobutylacrylate

EXAMPLE C-28

The polymerization is carried out in accordance with Example C-14 butwith the following changed comonomer composition: macromer of ExampleC-1/DMA/TRIS 33.3%/33.3%/33.3%. An optically clear polymer is obtained.

EXAMPLE D-1 Macromer Synthesis

In a dry box under nitrogen atmosphere, about 200 grams of dry PDMSdipropoxyethanol (Shin-Etsu) is added to a container. Isocyanatoethylmethacrylate (IEM) in an amount equal to about 2 moles per mole PDMSdialkanol is added to the container. About 0.1 weight percent dibutyltindilaurate (DBTL) catalyst, based on PDMS dialkanol weight, is added tothe container along with a stir bar. The container is immersed in an oilbath atop a stir plate, and secured in place with a clamp. A stream ofUPC air at about 2 psig is passed over the mixture. The mixture isagitated at room temperature (about 22° C.) for about 24 hours. Aniterative procedure follows in which the mixture is analyzed forisocyanate content and IEM is added if the PDMS dialkoxyalkanol has notbeen completely reacted. The mixture is stirred about 24 hours more. Themacromer produced is a siloxane-containing macromer.

EXAMPLE D-2 Lens fabrication

A prepolymerization mixture is prepared by mixing about 56 grams of themacromer from Example D-1, about 14 grams of TRIS, about 29 grams N,N-dimethylacrylamide (DMA), about 1 gram methacrylic acid, about 0.5grams Darocur® 1173 photoinitiator, and about 20 grams hexanol. Themixture is agitated for about 20 minutes at room temperature.

Next, the mixture is degassed via a series of freezing and thawingsteps. The container is placed in a liquid nitrogen bath until themixture solidifies. A vacuum is applied to the container at a pressureof about 200 millitorr or less for about 5 minutes. Then, the containeris placed in a bath of room temperature water until the mixture isliquid again. This process is performed a total of three times.

The mixture is then polymerized to form contact lenses. Theprepolymerization mixture is poured into polypropylene contact lensmolds in a nitrogen atmosphere. The polymerization is effected byapplying UV radiation (about 4-6 mW/cm²) for a period of about 15minutes.

The resulting fully hydrated contact lens has a water content of about23%. The lens has a Dk of about 115 barrers and a modulus of elasticityof about 2 MPa

EXAMPLE D-3 Lens fabrication

A contact lens is prepared in accordance with the procedure described inExample D-2, with the difference being that the composition is about 50%macromer of Example D-1, about 20% TRIS and about 30% DMA.

The resulting fully hydrated contact lens has a water content of about20%. The lens has a Dk of about 118 barrers and a modulus of elasticityof about 1.8 Mpa.

EXAMPLE E-1 Material A

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2. Prior to polymerization, theprepolymerization mixture is degassed by cooling the prepolymer mixturewith liquid nitrogen until the mixture solidifies and is near liquidnitrogen temperature, then applying a vacuum (about 0.1 mm Hg) to thesolidified prepolymer mixture, discontinuing the vacuum, and thawing theprepolymer mixture until the mixture is again in liquid form. Thisdegassing procedure is performed a total of three times on theprepolymerization mixture.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. The cured lens has an equilibrium water content of about19%. Subsequent to curing, the lens is plasma treated for about 10minutes in an atmosphere of methane and air at a 2:1 CH₄ :airvolume:volume ratio. The working pressure of the gas is about 50millitorr. The plasma treatment is accomplished in a PlasmaPolymerization Apparatus LCVD-20-400A (Plasmacarb, Bedford, Mass.).

The Ionoton Ion Permeability Coefficient of the lens is 0.81×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-2 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-10. Prior to polymerization, nitrogengas is bubbled through the prepolymer mixture in order to remove oxygenfrom the prepolymer mixture.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. The cured lens has an equilibrium water content of about26 weight percent. No coating is applied to the surface.

The Ionoton Ion Permeability Coefficient of the lens is -0.063×10⁻³ cm²/sec. Clinical examination shows that the lens does not move on thehuman eye. See Table E for a summary of the results.

EXAMPLE E-3 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-12. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. The cured lens has an equilibrium water content of about30 weight percent. Subsequent to curing, the lens is plasma treated forabout 3 minutes in an atmosphere of methane and air at a 2:1 CH₄ :airvolume ratio.

The Ionoton Ion Permeability Coefficient of the lens is 0.50×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-4 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-12. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. The cured lens has an equilibrium water content of about30 weight percent. Subsequent to curing, the lens is plasma treated forabout 7.5 minutes in an atmosphere of methane and air at a 2:1 CH₄ :airvolume ratio.

The Ionoton Ion Permeability Coefficient of the lens is 0.47×10⁻³ cm₂/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-5 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-12. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. The cured lens has an equilibrium water content of about30 weight percent. Subsequent to curing, the lens is plasma treated forabout 7.5 minutes in an atmosphere of methane and air at a 2:1 CH₄ :airvolume ratio.

The Ionoton Ion Permeability Coefficient of the lens is 0.35×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-6 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-11. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. The cured lens has an equilibrium water content of about30 weight percent The lens is not subsequently coated.

The Ionoton Ion Permeability Coefficient of the lens is 1.1×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-7 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-21. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. Subsequent to curing, the lens is plasma treated for about5 minutes in an atmosphere of methane and air at a 2:1 CH₄ :air volumeratio.

The Ionoton Ion Permeability Coefficient of the lens is 2.9×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-8 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-21. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. Subsequent to curing, the lens is plasma treated for about7.5 minutes in an atmosphere of methane and air at a 2:1 CH₄ :air volumeratio.

The Ionoton Ion Permeability Coefficient of the lens is 0.25×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-9 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-20. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in an air atmosphere to form the contactlens. Subsequent to curing, the lens is not surface treated.

The Ionoton Ion Permeability Coefficient of the lens is 0.008×10⁻³ cm²/sec. Clinical examination shows that the lens does not move on thehuman eye. See Table E for a summary of the results.

EXAMPLE E-10 Material D

A contact lens is prepared substantially in accordance with theprocedure described in Example D-2. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. Subsequent to curing, the lens is not surface treated.

The Ionoton Ion Permeability Coefficient of the lens is 1.4×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-11 Material D

A contact lens is prepared substantially in accordance with theprocedure described in Example D-2. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. Subsequent to curing, the lens is plasma treated for about7.5 minutes in an atmosphere of methane and air at a 2:1 CH₄ :air volumeratio.

The Ionoton Ion Permeability Coefficient of the lens is 0.61×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-12 Material D

A contact lens is prepared substantially in accordance with theprocedure described in Example D-2. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in a nitrogen atmosphere to form thecontact lens. Subsequent to curing, the lens is plasma treated for about5 minutes in an atmosphere of methane and air at a 2:1 CH₄ :air volumeratio.

The Ionoton Ion Permeability Coefficient of the lens is 1.5×10⁻³ cm²/sec. Clinical examination shows that the lens moves on the human eye.See Table E for a summary of the results.

EXAMPLE E-13 Material D

A contact lens is prepared substantially in accordance with theprocedure described in Example D-2. Prior to polymerization, theprepolymerization mixture is degassed by the repeated freeze/thawprocedure of Example E-1.

The prepolymer mixture is cured in an air atmosphere to form the contactlens. Subsequent to curing, the lens is not surface treated.

The Ionoton Ion Permeability Coefficient of the lens is -0.001×10⁻³ cm²/sec. Clinical examination shows that the lens does not move on thehuman eye. See Table E for a summary of the results.

                                      TABLE E                                     __________________________________________________________________________                             Surface                                                                       treatment                                                                           Ionoton Ion                                                             CH.sub.4 :air                                                                       Permeability                                                     Curing plasma                                                                              Coefficient                                                                           On-eye                                 Example                                                                             Material                                                                           Degassing                                                                            atmosphere                                                                           (minutes)                                                                           (10.sup.-3 cm.sup.2 /sec)                                                             Movement                               __________________________________________________________________________    E-1   A    3-cycle                                                                              nitrogen                                                                             10    0.81    YES                                               freeze/thaw                                                        E-2   B    nitrogen                                                                             nitrogen                                                                             no plasma                                                                           -0.063  NO                                                bubble                                                             E-3   B    3-cycle                                                                              nitrogen                                                                             3     0.50    YES                                               freeze/thaw                                                        E-4   B    3-cycle                                                                              nitrogen                                                                             5     0.47    YES                                               freeze/thaw                                                        E-5   B    3-cycle                                                                              nitrogen                                                                             7.5   0.35    YES                                               freeze/thaw                                                        E-6   B    3-cycle                                                                              nitrogen                                                                             no plasma                                                                           1.1     YES                                               freeze/thaw                                                        E-7   C    3-cycle                                                                              nitrogen                                                                             5     2.9     YES                                               freeze/thaw                                                        E-8   C    3-cycle                                                                              nitrogen                                                                             7.5   0.25    YES                                               freeze/thaw                                                        E-9   C    3-cycle                                                                              air    no plasma                                                                           0.008   NO                                                freeze/thaw                                                         E-10 D    3-cycle                                                                              nitrogen                                                                             no plasma                                                                           1.4     YES                                               freeze/thaw                                                         E-11 D    3-cycle                                                                              nitrogen                                                                             7.5   0.61    YES                                               freeze/thaw                                                         E-12 D    3-cycle                                                                              nitrogen                                                                             5     1.5     YES                                               freeze/thaw                                                         E-13 D    3-cycle                                                                              air    no plasma                                                                           -0.001  NO                                                freeze/thaw                                                        __________________________________________________________________________

Considering Examples E-1 through E-13 of Table E, the lowest value ofIonoton Ion Permeability Coefficient for which a lens moves on the eyeis 0.25×10⁻³ cm² /sec. The highest value of Ionoton Ion PermeabilityCoefficient for a lens which bound on the eye is 0.008×10⁻³ cm² /sec.Thus, a contact lens preferably has an Ionoton Ion PermeabilityCoefficient greater than about 0.008×10⁻³ cm² /sec., more preferablygreater than about 0.25×10⁻³ cm² /sec.

EXAMPLE F-1 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-25. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 0 mm²/min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone (PVP) in accordance with the followingprocedure, using a glass plasma reactor equipped with an external ringelectrode and a 27.13 MHz radio frequency (RF) generator for thegeneration of an inductively-coupled, cold glow discharge plasma. Highlypurified argon is used as a plasma gas and as a carrier gas forN-vinylpyrrolidone (NVP) monomer feed. The NVP feed line is locatedabout 10 cm below the glow zone.

The contact lens is placed in the 20 cm diameter plasma reactor at aposition about 15 cm below the plasma glow zone. The reactor is thenevacuated for about 30 minutes to about 0.009 mbar. Subquent toevacuation, the plasma gas flow is set to 20 sccm (standard cubiccentimeters), the glow discharge is started at a pressure of about 0.15mbar and maintained for about one minute at a power of about 170 Watts(in order to clean and activate the lens surface). After reduction ofargon plasma gas flow to about 10 sccm, the argon carrier gas flow forthe NVP monomer is also set to 10 sccm. The temperature of the NVPsource (with the carrier gas bubbling through the liquid NVP) is held atabout 40° C. The lenses are treated for about 10 minutes with a pulsingglow discharge plasma (1 μsec. on, 3 μsec. off) at about 0.35 mbarpressure and about 150 Watts power.

After interrupting the glow discharge and the carrier gas flow, thereactor is continuously purged with a 20 sccm argon steam at a pressureof about 0.009 mbar for about 30 minutes, in order to remove residualmonomer and activated species. The PVP coated contact lenses thusproduced are highly wettable and show the following dynamic contactangles, measured with a KRUESS (Hamburg, Germany) K-12 instrument:

    ______________________________________                                                     Untreated                                                                            Treated                                                   ______________________________________                                        Advancing      102      38                                                    Receding        48      23                                                    Hysterasis      53      15                                                    ______________________________________                                    

Clinical tests show that the lens does not move on the eye. See Table Ffor a summary of the results.

EXAMPLE F-2 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-26. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 2.8×10⁻⁷mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens does not move on the eye. See Table F for a summary of theresults.

EXAMPLE F-3 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-27. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 9.3×10⁻⁷mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens does not move on the eye. See Table F for a summary of theresults.

EXAMPLE F-4 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-18. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 2.6×10⁻⁶mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens moves on the eye. See Table F for a summary of the results.

EXAMPLE F-5 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-16. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 1.3×10⁻⁵mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens moves on the eye. See Table F for a summary of the results.

EXAMPLE F-6 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-19. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 2.7×10⁻⁵mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens moves on the eye. See Table F for a summary of the results.

EXAMPLE F-7 Material C

A contact lens is prepared substantially in accordance with theprocedure described in Example C-17. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 7.8×10⁻⁶mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens moves on the eye. See Table F for a summary of the results.

EXAMPLE F-8 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-13. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 1.5×10⁻⁶mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens does not move on the eye. See Table F for a summary of theresults.

EXAMPLE F-9 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-14. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 1.1×10⁻⁶mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens does not move on the eye. See Table F for a summary of theresults.

EXAMPLE F-10 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-7. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 3.8×10⁻⁶mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens moves on the eye. See Table F for a summary of the results.

EXAMPLE F-11 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-6. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 8.5×10⁻⁶mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens moves on the eye. See Table F for a summary of the results.

EXAMPLE F-12 Material B

A contact lens is prepared substantially in accordance with theprocedure described in Example B-5. Prior to surface treatment, theIonoflux Ion Permeability Coefficient is determined to be about 7.1×10⁻⁵mm² /min.

Subsequent to ion permeability measurements, the lens surface is coatedwith polyvinylpyrrolidone as in Example F-1. Clinical tests show thatthe lens moves on the eye. See Table F for a summary of the results.

                  TABLE F                                                         ______________________________________                                                MATERIAL   IONOFLUX ION                                                                              ON-EYE                                                 (Example   PERMEABILITY                                                                              MOVEMENT-                                              reference  COEFFICIENT*                                                                              CLINICAL                                       EXAMPLE number)    (mm.sup.2 /min)                                                                           DETERMINATION                                  ______________________________________                                        F-1     C-25       0           NO                                             F-2     C-26       0.28 × 10.sup.-6                                                                    NO                                             F-3     C-27       0.93 × 10.sup.-6                                                                    NO                                             F-4     C-18        2.6 × 10.sup.-6                                                                    YES                                            F-5     C-16       13.0 × 10.sup.-6                                                                    YES                                            F-6     C-19       27.0 × 10.sup.-6                                                                    YES                                            F-7     C-17        7.8 × 10.sup.-6                                                                    YES                                            F-8     B-13        1.5 × 10.sup.-6                                                                    NO                                             F-9     B-14        1.1 × 10.sup.-6                                                                    NO                                              F-10   B-7         3.8 × 10.sup.-6                                                                    YES                                             F-11   B-6         8.5 × 10.sup.-6                                                                    YES                                             F-12   B-5        71.0 × 10.sup.-6                                                                    YES                                            ______________________________________                                         *All Ionoflux Ion Permeability Coefficients were determined on uncoated       lenses.                                                                  

Considering only Examples F-1 through F-13 of Table F, the lowest valueof Ionoflux Ion Permeability Coefficient for which a lens moves on theeye is 2.6×10⁻⁶ mm² /min. The highest value of Ionoflux Ion PermeabilityCoefficient for a lens which binds on the eye is 1.5×10⁻⁶ mm² /min.Thus, a contact lens preferably has an Ionoflux Ion PermeabilityCoefficient greater than about 1.5×10⁻⁶ mm² /min., more preferablygreater than about 2.6×10⁻⁶ mm² /min.

EXAMPLE G-1

A contact lens is prepared substantially in accordance with theprocedure described in Example A-2. The Hydrodell Water PermeabilityCoefficient is determined to be about 0.71×10⁻⁶ cm² /second. Clinicaltests show that the lens moves on the eye. See Table G for a summary ofthe results.

EXAMPLE G-2

A contact lens is prepared substantially in accordance with theprocedure described in Example B-5. The Hydrodell Water PermeabilityCoefficient is determined to be about 1.09×10⁻⁶ cm² /second. Clinicaltests show that the lens moves on the eye. See Table G for a summary ofthe results.

EXAMPLE G-3

A contact lens is prepared substantially in accordance with theprocedure described in Example B-6. The lens is surface treated in aplasma gas in accordance with the procedure described in Example F-1.The Hydrodell Water Permeability Coefficient is determined to be about0.27×10⁻⁶ cm² /second. Clinical tests show that the lens moves on theeye. See Table G for a summary of the results.

EXAMPLE G-4

A contact lens is prepared substantially in accordance with theprocedure described in Example C-19. The lens is surface treated in aplasma gas in accordance with the procedure described in Example F-1.The Hydrodell Water Permeability Coefficient is determined to be about0.37×10⁻⁶ cm² /second. Clinical tests show that the lens moves on theeye. See Table G for a summary of the results.

EXAMPLE G-5

A contact lens is prepared substantially in accordance with theprocedure described in Example D-2. The Hydrodell Water PermeabilityCoefficient is determined to be about 1.26×10⁻⁶ cm² /second. Clinicaltests show that the lens moves on the eye. See Table G for a summary ofthe results.

EXAMPLE G-6

A contact lens is prepared substantially in accordance with theprocedure described in Example C-14. The Hydrodell Water PermeabilityCoefficient is determined to be about 0.08×10⁻⁶ cm² /second. Clinicaltests show that the lens does not move on the eye. See Table G for asummary of the results.

                  TABLE G                                                         ______________________________________                                                                  HYDRODELL ON-EYE                                          MATERIAL            WATER     MOVEMENT-                                       (Example  SURFACE   PERMEABILITY                                                                            CLINICAL                                  EX-   reference TREAT-    COEFFICIENT                                                                             DETER-                                    AMPLE number)   MENT      (cm.sup.2 /sec.)                                                                        MINATION                                  ______________________________________                                        G-1   A-2       none      0.71 × 10.sup.-6                                                                  YES                                       G-2   B-5       none      1.09 × 10.sup.-6                                                                  YES                                       G-3   B-6       PVP       0.27 × 10.sup.-6                                                                  YES                                       G-4    C-19     PVP       0.37 × 10.sup.-6                                                                  YES                                       G-5   D-2       none      1.26 × 10.sup.-6                                                                  YES                                       G-6    C-14     none      0.08 × 10.sup.-6                                                                  NO                                        ______________________________________                                    

Considering only Examples G-1 through G-6 of Table G, the lowest valueof Hydrodell Water Permeability Coefficient for which a lens moves onthe eye is 0.27×10⁻⁶ cm² /sec. The highest value of Hydrodell WaterPermeability Coefficient for a lens which binds on the eye is 0.08×10⁻⁶cm² /sec. Thus, a contact lens preferably has a Hydrodell WaterPermeability Coefficient greater than about 0.08×10⁻⁶ cm² /sec., morepreferably greater than 0.27×10⁻⁶ cm² /sec.

The invention has been described in detail, with reference to certainpreferred embodiments, in order to enable the reader to practice theinvention without undue experimentation. Theories of operation have beenoffered to better enable the reader to understand the invention, butsuch theories do not limit the scope of the invention. In addition, aperson having ordinary skill in the art will readily recognize that manyof the previous components, compositions, and parameters may be variedor modified to a reasonable extent without departing from the scope andspirit of the invention. Furthermore, titles, headings, examplematerials or the like are provided to enhance the reader's comprehensionof this document, and should not be read as limiting the scope of thepresent invention. Accordingly, the intellectual property rights to theinvention are defined by the following claims, reasonable extensions andequivalents thereof, as interpretted in view of the disclosure herein.

That which is claimed is:
 1. An ophthalmic lens, comprising an inner andouter surface, wherein said inner surface is adapted to rest immediatelyadjacent to the human cornea, wherein said lens has the followingproperties:(a) an oxygen permeability from said inner to said outersurface sufficient to prevent substantial corneal swelling during aperiod of extended wear; (b) ophthalmic compatibility during a period ofextended, continuous, intimate contact with the ocular environment; and(c) ion or water permeability sufficient to allow lens movement on theeye in an amount sufficient to sustain corneal health and wearercomfort,wherein said ophthalmic lens has an oxygen transmissibility ofat least about 70 barrers/mm and an ion permeability characterizedeither by (1) an Ionoton Ion Permeability Coefficient of greater thanabout 0.2×10⁻⁶ cm² /sec or (2) an Ionoflux Diffusion Coefficient ofgreater than about 1.5×10⁻⁶ cm² /min, wherein said ion permeability ismeasured with respect to sodium ions.
 2. An ophthalmic lens of claim 1,wherein said period of extended wear is at least 24 hours.
 3. Anophthalmic lens of claim 2, wherein said lens produces, after wear ofabout 24 hours, including normal sleep periods, less than about 8%corneal swelling.
 4. An ophthalmic lens of claim 3, wherein said lensproduces, after wear of about 24 hours, including normal sleep periods,less than about 6% corneal swelling.
 5. An ophthalmic lens of claim 4,wherein said lens produces, after wear of about 24 hours, includingnormal sleep periods, less than about 4% corneal swelling.
 6. Anophthalmic lens of claim 2, wherein said extended period of wear is atleast 4 days.
 7. An ophthalmic lens of claim 6, wherein said extendedperiod of wear is at least 7 days.
 8. An ophthalmic lens of claim 7,wherein said lens produces, after wear of about 7 days, including normalsleep periods, less than about 10% corneal swelling.
 9. An ophthalmiclens of claim 8, wherein said lens produces, after wear of about 7 days,including normal sleep periods, less than about 7% corneal swelling. 10.An ophthalmic lens of claim 9, wherein said lens produces, after wear ofabout 7 days, including normal sleep periods, less than about 5% cornealswelling.
 11. An ophthalmic lens of claim 1, wherein said period ofextended wear is at least 14 days.
 12. An ophthalmic lens of claim 11,wherein said extended period of wear is at least 30 days.
 13. Anophthalmic lens of claim 1, wherein said oxygen permeability (Dk) is atleast 80 barrers/mm.
 14. An ophthalmic lens of claim 1, wherein saidlens has a tensile modulus of 1.5 MPa or less.
 15. An ophthalmic lens ofclaim 1, wherein said lens has a short relaxation time constant ofgreater than about 3.5 seconds.
 16. An ophthalmic lens of claim 1,wherein the lens has a tan δ above about 0.25 at about 10 Hz.
 17. Anophthalmic lens of claim 1, wherein said lens has an Ionoton IonPermeability Coefficient of at least about 0.3×10⁻⁶ cm² /sec.
 18. Anophthalmic lens of claim 1, wherein said lens has an Ionoflux DiffusionCoefficient of greater than about 2.6×10⁻⁶ cm² /min.
 19. An ophthalmiclens of claim 1, wherein said lens has a Hydrodell Water PermeabilityCoefficient of greater than about 0.2×10⁻⁶ cm² /sec.
 20. An ophthalmiclens of claim 1, wherein said extended period of wear is at least 24hours and said oxygen transmissibility is at least 80 barrers/min, andwherein said lens has a tensile modulus of 1.5 MPa or less, a shortrelaxation time constant of 1.4 to 10 seconds, and an Ionoton IonPermeability Coefficient of at least 0.2×10⁻⁶ cm² /sec.
 21. Anophthalmic lens of claim 1, wherein said extended period of wear is atleast 4 days and said oxygen permeability (Dk) is at least 90barrers/mm, and wherein said lens has a tensile modulus of 1.5 MPa orless, a short relaxation time constant of greater than about 3.5seconds, and an Ionoton Ion Permeability Coefficient of at least0.4×10⁻⁶ cm² /sec.
 22. An ophthalmic lens of claim 1, wherein saidextended period of wear is at least 4 days and said oxygen permeability(Dk) is at least 90 barrers/mm, and wherein said lens has a tensilemodulus of 1.5 MPa or less, a short relaxation time constant of greaterthan about 3.5 seconds, and an Ionoflux Diffusion Coefficient of greaterthan about 1.5×10⁻⁶ mm² /min.
 23. An ophthalmic lens of claim 1, whereinsaid extended period of wear is at least 4 days and said oxygenpermeability (Dk) is at least 90 barrers/mm, and wherein said lens has atensile modulus of 1.5 MPa or less, a short relaxation time constant ofgreater than about 3.5 seconds, and a Hydrodell Water PermeabilityCoefficient of greater than about 0.2×10⁻⁶ cm² /sec.